1 For example, a recent study of awards by the International Centre for Settlement of Investment Disputes (ICSID) found that 94 percent and 74 percent relied on case law and academic authorities, respectively, while only a handful relied on subsequent practice and agreements by treaty parties. Ole Kristian, Fauchald The Legal Reasoning of ICSID Tribunals: An Empirical Analysis , 19 Eur. J. Int’l L. 301, 328-33, 335, 351 (2008).Google Scholar

2 Vienna Convention on the Law of Treaties, Art. 31(3)(a), (b), opened for signature May 23,1969,1155 UNTS 331 [hereinafter Vienna Convention] (entered into force Jan. 27, 1980). Subparagraphs (a) and (b) of Article 31 are quoted infra in text at note 94. Article 31(3)(c) requires reference to other relevant rules of international law, including custom, but this article does not address these rules because they raise distinct issues better treated at length on a separate occasion.

3 North American Free Trade Agreement, Can.-Mex.-U.S., Dec. 8, 11, 14, & 17, 1992, 32 ILM 289 & 605 (1993) [hereinafter NAFTA].

4 NAFTA Free Trade Commission, Notes of Interpretation of Certain Chapter 11 Provisions (July 31, 2001), available at http://www.international.gc.ca/trade-agreements-accorcls-commerciaux/c!isp-diff/NAFTA-Interpr.aspx?lang=en Google Scholar. In broad terms, the FTC interpretation “clarified] and reaffirm [ed]” that (1) NAFTA does not impose a general duty of confidentiality on the disputing parties to Chapter 11 arbitrations or preclude the treaty parties from providing public access to documents submitted to, or issued by, a Chapter 11 tribunal; and (2) the minimum standard of treatment provided for in Article 1105 prescribes the customary international law minimum standard of treatment of aliens, the requirements of “fair and equitable treatment” and “full protection and security” referred to in that article do not require treatment above and beyond that minimum standard under customary international law, and a determination that there was a breach of another NAFTA provision or international agreement does not establish a breach of Article 1105. The latter interpretations were particularly controversial because they effectively overruled interpretations adopted, against the pleadings and interventions of the treaty parties, by certain Chapter 11 tribunals.

5 NAFTA, supra note 3, Arts. 1131(2), 2001(1) & (2)(c).

6 Pope & Talbot Inc. v. Canada, Damages, para. 47 (NAFTA Ch. 11 Arb. Trib. May 31, 2002), 41 ILM 1347 (2002) [hereinafter Pope & Talbot Damages] (holding that, “were the Tribunal required to make a determination whether the Commission’s action is an interpretation or an amendment, it would choose the latter. However, for the reasons discussed below, this determination is not required.”) (footnote omitted).

7 Id., paras. 11-16. The tribunal asked how such a process could be squared with the “rule of international law that no-one shall be judge in his own cause” and the purpose of the arbitral mechanism to “assure due process before an impartial tribunal.” Id., para. 13. The timing of the FTC interpretation caused particular concern to the tribunal because it was adopted after the tribunal reached a contrary decision on interpretation during the merits phase and was forwarded to the tribunal for consideration before the damages phase.

8 ADF Group Inc. v. United States, ICSID No. ARB(AF)/00/l, para. 177 (NAFTA Ch. 11 Arb. Trib. Jan. 9, 2003), 18 ICSID Rev. 195 (2003) [hereinafter ADF Group]. Many, but not all, details of ICSID arbitrations are available on the ICSID Web site, http://www.worldbank.org/icsid/. When cases referenced below are available in print form, that source will be cited. Cases cited below for which neither a print nor another online source is given here are available on the ICSID Web site.

9 ADF Group, supra note 8, para. 177 (also noting the “systemic need not only for a mechanism for correcting what the Parties themselves become convinced are interpretative errors but also for consistency and continuity of interpretation, which multiple ad hoc arbitral tribunals are not well suited to achieve and maintain”).

10 See Guillermo Aguilar, Alvarez & William, W. Park The New Face of Investment Arbitration: NAFTA Chapter 11 , 28 Yale J. Int’l L. 365, 397–400 (2003)Google Scholar; Charles, H. Brower II Investor-State Disputes Under NAFTA: The Empire Strikes Back , 40 Colum. J. Transnat’l L. 43, 56 n.71 (2001)Google Scholar [hereinafter Brower II, Empire Strikes Back]; Charles, H. Brower II Why the FTC Notes of Interpretation Constitute a Partial Amendment of NAFTA Article 1105 , 46 VA. J. Int’l L. 347 (2006) [hereinafter Brower II, FTC Notes]Google Scholar; Stefan, Matiation Arbitration with Two Twists: Loewen v. United States and Free Trade Commission Intervention in NAFTA Chapter 11 Disputes , 24 U. Pa. J. Int’l Econ. L. 451, 487–88, 494–95 (2003)Google Scholar; William, W. Park The Specificity ofInternational’Arbitration: The Case for FAA Reform , 36 Vand. J. Transnat’l L. 1241, 1304–05 (2003)Google Scholar; J. C., Thomas A Reply to Professor Brower , 40 Colum. J. Transnat’l L. 433, 453–55 (2002)Google Scholar; Todd, Weiler NAFTA Investment Arbitration and the Growth of International Economic Law , 2002 Bus. L. Int’l 158, 180–85 Google Scholar; Todd, Weiler NAFTA Investment Law in 2001: As the Legal Order Starts to Settle, the Bureaucrats Strike Back , 36 Int’llaw. 345, 346–48 (2002)Google Scholar; Courtney, C. Kirkman Note, Fair and Equitable Treatment: Methanex v. United States and the Narrowing Scope of NAFTA Article 1105 , 34 Law & Pol’y Int’l Bus. 343, 381–83, 391 (2002)Google Scholar.

11 Despite the significance of this controversial issue, it has not received sustained attention or critique. Most investment treaty awards and commentaries hardly discuss appropriate interpretive approaches and, when they do, they tend to focus primarily on the “ordinary meaning” and “object and purpose” of investment treaties and die relevance of customary international law and travaux préparatoires. The interpretive relevance of subsequent agreements and practice is not commonly analyzed, with the notable exception of the FTC’s Notes of Interpretation. The issue, however, has received some attention in Rudolf, Dolzer & Christoph, Schreuer Principles of International Investment Law 34–35 (2008)Google Scholar; Andrew, Newcombe & Llufs, Paradell Law and Practice of Investment Treaties: Standards of Treatment 117-19, §2.30 (2009)Google Scholar; Gus Van, Harten investment Treaty Arbitration and Public Law 126-28 (2007)Google Scholar; and Fauchald, supra note 1, at 328-29, 343-48.

12 This article focuses on investor-state disputes arising out of bilateral and multilateral investment treaties only. It does not consider the nature of investor-state contracts or the possible impact that these may have on interpretive methods, nor does it examine state-state disputes in detail. The vast majority of investment treaties are bilateral, but some important ones are multilateral. These tend to be regional, such as NAFTA, or sectoral, such as the Energy Charter Treaty.

13 The treaty parties do not have exclusive power to select the arbitrators because, while the treaty parties consent to investor-state arbitration in general, investor-state tribunals are ad hoc bodies whose members are selected by the disputing parties (which includes one treaty party) and/or appointing institutions. This procedure reduces the treaty parties’ control over the selection of arbitrators and increases the possibility that arbitrators will see their principals only as the disputing parties rather than also as the treaty parties. See David, D. Caron Towards a Political Theory of International Courts and Tribunals , 24 Berkeley J. Int’l L. 401, 403–04 (2006)Google Scholar (discussing the difference between party-originated and community-originated dispute resolution).

14 Mavrommatis Palestine Concessions (UK v. Greece), 1924 Pcij (ser. A) No. 2, at 12 (Aug. 30) Google Scholar; Edwin, M. Borchard The Diplomatic Protection of Citizens Abroad, or, the Law of International Claims 354 (1919)Google Scholar; l Emer De, Vattel Le Droit Des Gens ou les Principes de la loi Naturelle, bk. II, ch. VI, §71, at 309 (Carnegie ed. 1916) (1758)Google Scholar. Decisions and other documents cited below of the Permanent Court of International Justice (PCIJ) and the International Court of Justice (ICJ) are available at the latter’s Web site, http://www.icj-cij.org.

15 Barcelona Traction, Light & Power Co. (Belg. v. Spain), Second Phase, 1970 ICJ Rep. 3, 44, paras. 78-79 (Feb. 5).

16 Some treaties curtail the right of home states to exercise diplomatic protection when the investor and host state have consented to arbitration. See, e.g., Convention on the Settlement of Investment Disputes Between States and Nationals of Other States, Art. 27(1), Mar. 18, 1965,17 UST 1270, 575 UNTS 159 [hereinafter ICSID Convention] .

17 Robert, O. Keohane Andrew, Moravcsik & Anne-Marie, Slaughter Legalized Dispute Resolution: Interstate and Transnational , 54 Int’l Org. 457, 457–58 (2000)Google Scholar (defining “interstate” dispute resolution as involving disputes between states, and “transnational” dispute resolution as involving disputes between nonstate actors and states).

18 The main exception discussed in the literature is a 2003 state-state dispute between Chile and Peru that was lodged in response to an investor-state claim by a Chilean company, Empresas Lucchetti S.A. v. Peru, ICSID No. ARB/03/4, but later discontinued. United Nations Conference on Trade and Development [UNCTAD], Latest Developments in Investor-State Dispute Settlement, IIA Monitor, No. 4, 2005, at 2 n.3.

19 Zachary, Douglas The International Law of investment Claims 6, para. 6 (2009)Google Scholar [hereinafter Douglas, Investment Claims]; Van Harten, supra note 11, at 124 -36; Zachary, Douglas The Hybrid Foundations of Investment Treaty Arbitration , 2003 Brit. Y.B. Int’l L. 151, 152–53 Google Scholar [hereinafter Douglas, Hybrid Foundations). Similar difficulties occurred in attempts to pigeonhole the Iran-United States Claims Tribunal as involving either public international law arbitration (because it was based on an interstate treaty) or private international law arbitration (because claims were brought by nonstate actors). See David, D. Caron The Nature of the Iran-United States Claims Tribunal and the Evolving Structure of International Dispute Resolution , 84 Ajil 104, 105–07, 156 (1990)Google Scholar (arguing that this public/private dichotomy is inadequate to explain developments like arbitration before the Iran-U.S. Claims Tribunal and ICSID tribunals).

20 Keohane, Moravcsik, & Slaughter, supra note 17, at 459; see also Van Harten, supra note 11, at 96 - 99 (discussing the lack of control by states over potential claims and arguments made by investors).

21 See, e.g., David, Schneiderman Constitutionalizing Economic Globalization: investment Rules and Democracy’s Promise (2008)Google Scholar; Van Harten, supra note 11; Benedict, Kingsbury & Stephan, Schill Investor-State Arbitration as Governance: Fair and Equitable Treatment, Proportionality and the Emerging Global Administrative Law (New York Univ. Pub. Law & Theory Working Papers, 2009), available at http://lsr. nellco.org/nyu_plltwp/l46/ Google Scholar.

22 Treaties can grant nonstate actors substantive rights, procedural rights, neither type of right, or both types of right. For example, the Vienna Convention on Consular Relations grants substantive rights to individuals but permits international claims to be brought only by states. LaGrand (FRG v. U.S.), 2001 ICJ Rep. 466, para. 77 (June 27). By contrast, the European Convention on Human Rights grants substantive rights to persons and permits them to bring direct claims against states before the European Court of Human Rights. See European Convention for the Protection of Human Rights and Fundamental Freedoms, Arts. 1-18, 34, Nov. 4, 1950, Europ. TS No. 5, 213 UNTS221 [hereinafter ECHR].

23 Douglas, Investment Claims, supra note 19, at 10-32, paras. 13-64; Andrea, K. Bjorklund Private Rights and Public International Law: Why Competition Among International Economic Law Tribunals Is Not Working , 59 Hastings L. J. 241, 263–70 (2007)Google Scholar; Douglas, Hybrid Foundations, supra note 19, at 162-64; Susan, D. Franck Foreign Direct Investment, Investment Treaty Arbitration, and the Rule of Law , 19 Pac. Mcgeorge Global Bus. & Dev. L. J. 337, 343–44 (2006)Google Scholar. For case law on the different positions, compare Corn Prods. Int’l v. Mexico, ICSID No. ARB(AF)/04/01, Decision on Responsibility, paras. 166-69 (NAFTA Ch. 11 Arb.Trib. Jan. 15, 2008) (investors are granted substantive and procedural rights), and Ecuador v. Occidental Exploration & Prod. Co., [2006] EWHC 345 (Comm), [2006] Q.r3- 432, paras. 14-22 (same), with Loewen Group, Inc. v. United States, ICSID No. ARB(AF)/98/3, para. 233 (NAFTA Ch. 11 Arb. Trib. June 26, 2003), available at http://www.state.gov/s/l/c3741.htm [hereinafter loewen], and Archer Daniels Midland Co. v. Mexico, ICSID No. ARB(AF)/04/5, paras. 168-80 (NAFTA Ch. 11 Arb. Trib., redacted version Nov. 21, 2007) (investors are granted procedural, not substantive rights). Similar debates occurred with respect to whether individual claims could be brought before the Iran- U.S. Claims Tribunal. See Caron, supra note 19, at 131-37.

24 For example, Van Harten argues that, to implement the interstate bargain, “where die states parties make unanimous submissions about how the treaty should be interpreted, tribunals should adopt their view as a matter of course” and a “tribunal should be cautious about adopting interpretations in favour of investor protection that go beyond the submissions of the investor’s home state.” Van Harten, supra note 11, at 131-32.

25 Arguing for greater use of such evidence is not the same as proposing that the system of diplomatic protection and home state espousal be reintroduced. Permitting investors to bring direct claims has bypassed many of the problems with the traditional model, including home state control of claims. See Charles, N. Brower & Stephan, W. Schill Is Arbitration a Threat or a Boon to the legitimacy of International Investment law : 9 Chi. J. Int’l L. 471, 477–83 (2009)Google Scholar. But the movement away from diplomatic protection does not undermine the legitimate legal interest of home states, host states, and other treaty parties in interpretation.

26 Alec Stone Sweet, Constitutionalism, Rights, and Judicial Power , in Comparative Politics 217, 228–29 (Daniele, Caramani ed., 2008).Google Scholar

27 See, e.g., Jacob, Katz Cogan Competition and Control in International Adjudication , 48 Va. J. Int’l L. 411 (2008)Google Scholar; Allison, Marston Danner When Courts Make law: How the International Criminal Tribunals Recast the Laws of War , 59 Vand. L. Rev. 1 (2006)Google Scholar; Tom, Ginsburg Bounded Discretion in International Judicial Lawmaking , 45 VA. J. Int’l L. 631 (2005)Google Scholar; Eric, A. Posner & John C., Yoo Judicial Independence in International Tribunals , 93 Cal. L. Rev. 1, 7 (2005) [hereinafter, Posner & Yoo, I]Google Scholar; Laurence, R. Heifer & Anne-Marie, Slaughter Why States Create International Tribunals: A Response to Professors Posner and Yoo , 93 Cal. L. Rev. 899, 942–54 (2005)Google Scholar; Eric A., Posner & John, C. Yoo Reply to Heifer and Slaughter , 93 Cal. L. Rev. 957 (2005) [hereinafter, Posner & Yoo, II]Google Scholar; Richar, H. Steinberg Judicial Lawmaking at the WTO: Discursive, Constitutional, and Political Constraints , 98 Ajil 247, 249 (2004)Google Scholar; Paul, B. Stephan Courts, Tribunals, and Legal Unification—The Agency Problem , 3 Chi. J. Int’ll. 333 (2002)Google Scholar. See generally Curtis, A. Bradley & Judith, G. Kelley The Concept of International Delegation , Law & Contemp. Probs., Winter 2008, at 1.Google Scholar

28 Rational choice models have been very influential in shaping our understanding of why states enter into investment treaties. See, e.g., Zachary, Elkins Andrew, T. Guzman & Beth, A. Simmons Competing for Capital: The Diffusion of Bilateral Investment Treaties, 1960-2000 , 60 Int’l Org. 811 (2006)Google Scholar; Andrew, T. Guzman Why LDCs Sign Treaties That Hurt Them: Explaining the Popularity of Bilateral Investment Treaties , 38 Va. J. Int’l L. 639 (1998)Google Scholar. However, questions exist about the accuracy of the assumptions made in the models, for example, whether states act rationally when entering into investment treaties. See, e.g., Republic of South Africa, Bilateral Investment Treaty Policy Framework Review: Government Position Paper 5 (June 2009), available at http://www.pmg.org.za/files/docs/090626trade-bi-lateralpolicy.pdf Google Scholar (finding that South Africa entered into many BITs “that were not in [its] long term interest” because “the risks posed by such treaties were not fully appreciated at that time” and the “Executive had not been fully apprised of all the possible consequences of BITs”); Lauge, Skovgaard Poulsen & Damon, Vis-Dunbar Reflections on Pakistan’s Investment-Treaty Program After 50 Years: An Interview with the Former Attorney General of Pakistan, Makhdoom Ali Khan , Investment Treaty News, Apr. 2009, at 3, 3–4 Google Scholar (discussing Pakistan’s “haphazard and piecemeal” approach to signing BITs, often with no evidence of “meaningful negotiations” and “without seriously considering the implications”). On the appropriateness of applying a bounded rationality theory in the investment treaty context, see Lauge Skovgaard Poulsen, Why Do Developing Countries Sign BITs? A Bounded Rationality Approach (2009) (unpublished student working paper) (on file with author).

29 Danner, supra note 27, at 42; Ginsburg, supra note 27, at 641-44; Posner & Yoo I, supra note 27, at 6-7, 14; Posner & Yoo II, supra note 27, at 958.

30 Kenneth, W. Abbott Robert, O. Keohane Andrew, Moravcsik Anne-Marie, Slaughter & Duncan, Snidal The Concept of Legalization , 54 Int’l Org. 401, 415–18 (2000)Google Scholar; Kenneth, W. Abbott & Duncan, Snidal HardandSoft Law in International Governance , 54 Int’l Org. 421 (2000)Google Scholar; Karen, J. Alter Agents or Trustees?International Courts in Their Political Context , 14 Eur. J. Int’l Rel. 33, 38–39 (2008)Google Scholar [hereinafter Alter, Agents or Trustees?]; Karen, J. Alter Delegation to International Courts and the Limits of Re-contracting Political Power , in Delegation and Agency in International Organizations 312, 326–29 (Darren, G. Hawkins David, A. Lake Daniel, L. Nielson & Michael, J. Tierney eds., 2006)Google Scholar; Cogan, supra note 27, at 416; Heifer & Slaughter, supra note 27, at 917, 933-34.

31 It is also affected by other factors, not considered in this article, such as predictability and coherence of decision making, accountability of judges, and openness of the procedure to relevant stakeholders. See generally Van, Harten supra note 11, at 152-75Google Scholar; Charles, H. Brower II Structure, Legitimacy, and NAFTA’s Investment Chapter , 36 Vand. J. Transnat’l L. 37, 51-57 (2003).Google Scholar

32 See Stone Sweet, supra note 26, at 220 -21, 227-28 (noting, however, that many domestic courts fall between these extremes).

33 See Ginsburg, supra note 27, at 670-73; Alec, Stone Sweet & Florian, Grisel Transnational Investment Arbitration: From Delegation to Constitutionalization? in Human Rights in International Investment Law and Arbitration 118, 122 (Pierre-Marie, Dupuy Francesco, Francioni & Ernst-Ulrich, Petersmann eds., 2009)Google Scholar (arguing that the requirement in many multilateral treaties that amendments be approved unanimously makes the zone of discretion for international courts and tribunals charged with interpreting and applying those treaties wider than that of many domestic constitutional courts).

34 Alter, Agents or Trustees? supra note 30, at 39-40. Alter argues that trustees are (1) selected because of their personal reputation or professional norms (which means that they may bring some of their own authority with them, such as rational-legal authority if they are viewed as disinterested actors applying preexisting rules in a like fashion); (2) given independent authority to make decisions according to their best judgment or professional criteria; and (3) empowered to act on behalf of a beneficiary (which is particularly likely where a treaty grants rights to nonstate actors).

35 Cogan, supra note 27, at 414.

36 Ginsburg, supra note 27, at 632 (“international judges exercise bounded discretion in lawmaking”); Heifer & Slaughter, supra note 27, at 930 (even independent tribunals operate within a zone of “constrained independence”); Steinberg, supra note 27, at 249 (even a highly independent tribunal like the WTO Appellate Body operates within a “strategic space” bounded by “legal discourse, which could be constrained by constitutional rules, both of which are constrained by politics”); see Caron, supra note 13, at 411, & C infra note 75; see also Harold, D. Lasswell & Myres, S. Mcdougal Jurisprudence for a Free Society: Studies in Law, Science and Policy 24–27 (1992)Google Scholar (discussing “authoritative decisions” as being based on a dynamic of “authority and control”).

37 See Martin, Shapiro Courts: A Comparative and Political Analysis 28-36 (1981)Google Scholar; Martin, Shapiro & Alec, Stone Sweet on Law, Politics, and Judicialization 90–135 (2002)Google Scholar; Caron, supra note 13, at 406-10; Ginsburg, supra note 27, at 635.

38 ICJ Statute, Art. 38(l)(d); PCIJ Statute, Art. 38. As Baron Descamps stated when negotiating this provision of the PCIJ Statute, on which the ICJ Statute’s provision is based: “Doctrine and jurisprudence no doubt do not create law; but they assist in determining rules which exist. A judge should make use of both jurisprudence and doctrine, but they should serve only as elucidation.” PCIJ, Advisory Committee of Jurists, 15th mtg. (July 3, 1920), Procès-Verbaux of the Proceedings of the Committee 336 (June 16-July 24, 1920). The list of sources set out in these Statutes is often taken as the list of sources of international law more generally. See Ian, Brownlie Principles of Public International Law 5 (7th ed. 2008)Google Scholar; Peter, Malanczuk Akehurst’s Modern Introduction to International Law 36 (7th rev. ed. 1997)Google Scholar; 1 Oppenheim’s International Law 24, para. 9 (Robert, Jennings & Arthur, Watts eds., 9th ed. 1996)Google Scholar [hereinafter Oppenheim].

39 Alan, Boyle & Christine, Chinkin The Making of International Law 268 (2007).Google Scholar

40 ICJ Statute, Arts. 38(l)(d), 59.

41 See, e.g., ECHR, supra note 22, Art. 32(1) (giving the European Human Rights Court jurisdiction to interpret and apply the ECHR). Numerous treaties give the ICJ jurisdiction to interpret and apply their provisions, such as the Convention on the Prevention and Punishment of the Crime of Genocide, Art. IX, Dec. 9, 1948, S. EXEC. Rep. NO. 50, 98th Cong. (1984), 78 UNTS 277, and the International Convention on the Elimination of All Forms of Racial Discrimination, Art. 22, Dec. 21, 1965, S. Exec. DOC. NO. 95-C (1978), 660 UNTS 195.

42 H. L. A. Hart, The Concept of Law 121-50 (1961); Shapiro, supra note 37, at 28-29; Caron, supra note 13, at 407; Heifer & Slaughter, supra note 27, at 937; Alec Stone Sweet, Path Dependence, Precedence, and Judicial Power, in Shapiro & Stone Sweet, supra note 37, at 112.

43 The wide influence of judicial interpretations helps to explain why nondisputing states are often entitled to intervene in cases before international courts that involve the interpretation of treaties to which they are a party. See, e.g., ICJ Statute, Art. 63; Christine, Chinkin Article 63, in The Statute of The International Court of Justice: A Commentary 1369, 1370–71 (Andreas, Zimmermann Christian, Tomuschat & Karin, Oellers-Frahm eds., 2006)Google Scholar; of. ICJ Statute, Art. 62 (allowing states that believe they have an interest of a legal nature that may be affected by the decision in the case to request permission to intervene but leaving it to the Court to decide).

44 See Douglas, Investment Claims, supra note 19, at 3 nn.6, 7. This more limited mandate is distinct from the “interpret and apply” mandate generally given to international courts and to state-state investment tribunals. Some investment treaties specifically preclude giving awards precedential status, but others are silent on the issue. See, e.g., NAFTA, supra note 3, Art. 1136( 1); ICSID Convention, supra note 16, Art. 53. The ad hoc nature of investment tribunals, coupled with the largely bilateral treaty basis, makes the system particularly ill-suited to a strict precedent doctrine.

45 Investment tribunals are increasingly citing and distinguishing prior awards in reaching their decisions. See Jeffery, P. Commission Precedent in Investment Treaty Arbitration: A Citation Analysis of a Developing Jurisprudence , 24 J. Int’l Arb. 129, 148–50 (2007)Google Scholar (the average number of cases cited per award has grown enormously); Fauchald, supra note 1, at 335 (ninety-two out of ninety-eight ICSID awards used case law as an interpretive argument). A review of the leading textbooks in the field demonstrates the extent to which academics and practitioners look to awards to explain investment treaty obligations. Pleadings filed in investor-state arbitrations are replete with argumentation based on awards, whether filed by claimant investors or respondent states.

46 On precedent in investment treaty law, see generally Tai-Heng, Cheng Precedent and Control in Investment Treaty Arbitration , Investment Treaty Law: Current Issues III, at 147 (2009)Google Scholar; Gabriele, Kaufmann-Kohler Arbitral Precedent: Dream, Necessity orExcuse? 23 Arb. Int’l 357 (2007)Google Scholar; Catherine, Kessedjian To Give or Not to Give Precedential Value to Investment Arbitration Awards? in The Future of Investment Arbitration 43 (Catherine, A. Rogers & Roger, P. Alford eds., 2009)Google Scholar; Christoph, Schreuer & Matthew, Weiniger A Doctrine of Precedent? in The Oxford Handbook of International Investment Law 1188, 1189–91 (Peter, Muchlinski Federico, Ortino & Christoph, Schreuer eds., 2008)Google Scholar; Precedent in InvestmentArbitration , Transnat’ldlsp. Mgmt., May 2008 (special issue).Google Scholar

47 Abbott, Keohane, Moravcsik, Slaughter, & Snidal, supra note 30, at 401-02.

48 For background on the distinction between rules and standards, see Louis, Kaplow Rules Versus Standards: An Economic Analysis , 42 Duke L. J. 5 57, 559–60 (1992)Google Scholar; Duncan, Kennedy Form and Substance in Private Law Adjudication , 89 Harv. L. Rev. 1685, 1687–89 (1976)Google Scholar; Joel, P. Trackman The Domain of WTO Dispute Resolution , 40 Harv. Int’l L. J. 333, 335, 350–52 (1999)Google Scholar; Anne, van Aaken International Investment Law Between Commitment and Flexibility: A Contract Theory Analysis , 12 J. Int’l Econ. L. 507, 515–19 (2009)Google Scholar. There can be many reasons why treaty parties may have initially chosen standards instead of rules, but this choice is not analyzed here.

49 Abbott, Keohane, Moravcsik, Slaughter, & Snidal, supra note 30, at 414-15; Trachtman, supra note 48, at 3 3 5 n . l l .

50 Abbott, Keohane, Moravcsik, Slaughter, & Snidal, supra note 30, at 415; Keohane, Moravcsik, & Slaughter, supra note 17, at 461-62; Trachtman, supra note 48, at 335; van Aaken, supra note 48, at 519.

51 Abbott, Keohane, Moravcsik, Slaughter, & Snidal, supra note 30, at 413; see also Van Harten, supra note 11, at 122-23; Trachtman, supra note 48, at 335, 350-55. Unctad suggests that “the increase in investment disputes has tested the wisdom of negotiating [investment treaties] with extremely broad and imprecise provisions.” Unctad, Investor-State Dispute Settlement and Impact on Rulemaking 92, UN Sales No. E.07.II.D.10 (2007) (“The broader and more imprecise a particular text is, the more likely that it will lead to different, and even conflicting, interpretations. This will increase not only the likelihood of a dispute arising between the investor and the host country, but also the possibility of delegating to the arbitral tribunal the task of identifying the meaning that the disputed provision should have.”).

52 See Fauchald, supra note 1, at 328-29, 335, 343-49, 351; Kingsbury & Schill, supra note 21, at 2.

53 Andrea, K. Bjorklund Investment Treaty Arbitral Decisions as Jurisprudence Constante, in International Economic Law: the State and Future of The Discipline 265, 266 (Colin, B. Picker Isabella, D. Bunn & Douglas, W. Arner eds., 2008)Google Scholar; see also Campbell, McLachlan Investment Treaties and General International Law , 57 Int’l & Comp. L. Q. 361, 379 (2008)Google Scholar; J., Paulsson International Arbitration and the Generation of Legal Norms: Treaty Arbitration and International Law , Transnat’l Disp. Mgmt., Dec. 2006 Google Scholar (less notable decisions will “doubtless turn out to be subject to the same Darwinian reality: the unfit will perish”); Christoph, Schreuer Diversity and Harmonization of Treaty Interpretation in Investment Arbitration , Transnat’l Disp. Mgmt., Apr. 2006, at 1, 17.Google Scholar

54 Bjorklund appears to assume that the views of states will be communicated through their arbitration counsel, but states should have broader means of asserting their interpretive views than simply by submitting briefs in investor- state disputes. One reason their wider interpretive role tends to be sidelined is that states rarely insert themselves into the ongoing critique of investment standards, except when they are disgruntled respondents, which leads other participants in the process to view them primarily as respondents rather than also as treaty parties.

55 See, e.g., Van Harten, supra note 11, at 152-75; Anthony, DePalma NAFTA’s Powerful little Secret; Obscure Tribunals Settle Disputes but Go Too Far, Critics Say , N.Y. Times, Mar. 11, 2001, §3, at 1Google Scholar; Sarah, Anderson & Sara, Grusky Challenging Corporate Investor Rule: How the World Bank’s Investment Court, Free Trade Agreements, and Bilateral Investment Treaties Have Unleashed a New Era of Corporate Power and What to Do About It (Apr. 1, 2007), at http://www.ips-dc.org/reports/challenging_corporate_investor_rule.Google Scholar

56 J. H. H., Weiler The Transformation of Europe , 100 Yale L. J. 2403, 2411 (1991)Google Scholar (drawing on Albert, O. Hlrschman Exit, Voice and Loyalty: Responses to Decline in Firms, Organizations, and States (1970)Google Scholar). Although Hirschman developed his theory for the marketplace, he indicated that it could be applicable to any organizational setting. Id. at 2411. See also Ginsburg, supra note 27, at 657-68; van Aaken, supra note 48, at 509.

57 ICSID Convention, supra note 16.

58 See generally Laurence, R. Heifer Exiting Treaties , 91 Va. L. Rev. 1579 (2005)Google Scholar.

59 In a seminal article, Jan Paulsson identified the precariousness of investment treaty arbitration, whose prospects may turn in future on whether states, which may not have fully grasped the implications of their new treaty obligations, “take fright and reverse tracks.” Whether that happens may depend on “the degree of sophistication shown by arbitrators when called upon to pass judgment on governmental actions. Arbitration without privity is a delicate mechanism. A single incident of an adventurist arbitrator going beyond the proper scope of his jurisdiction in a sensitive case may be sufficient to generate a backlash.” Jan, Paulsson Arbitration Without Privity , 10 Icsid Rev. 232, 257 (1995)Google Scholar (emphasis added). On more recent concerns, see The Backlash Against Investment Arbitration: Perceptions and Reality (Michael, Waibel Asha, Kaushal Kyo-Hwa, Chung & Claire, Balchin eds., 2010)Google Scholar [hereinafter Backlash].

60 For example, Bolivia and Ecuador have withdrawn from the ICSID Convention, and other states (such as Nicaragua and Venezuela) have mooted doing likewise. See List of Contracting States and Other Signatories of the Convention 4, note (Jan. 7, 2010), at http://icsid.worldbank.org/ICSID/Index.jsp. Some countries, including Ecuador and Venezuela, have reportedly withdrawn from or sought to renegotiate a number of their investment treaties. See UNCTAD, Recent Developments in International Investment Agreements (2007-June 2008), Iia Monitor No. 2, 2008, at 6.Google Scholar Others have suspended further negotiations of investment treaties pending reviews of their policy frameworks. See, e.g., Republic of South Africa, supra note 28, at 12.

61 In the trade context, for example, the exit option may not be practicable if it involves shutting the state out of vital markets. See Steinberg, supra note 27, at 267.

62 Hirschman, supra note 56, at 30-31; Weiler, supra note 56, at 2411.

63 Hirschman, supra note 56, at 33-34, 82-86.

64 According to UNCTAD, in 2007, “10 of the 44 new BITs (23 per cent) replaced earlier treaties.” As of the end of 2007, 121 BITs had been renegotiated, less than 5 percent of the total of 2608. UNCTAD expected “ [t] his number . . . to rise further since a growing number of BITs are nearing expiry of their initial period of validity, and more countries are revising their model BITs to reflect new concerns related to environmental and social issues, including the host country’s right to regulate.” UNCTAD, supra note 60, at 5.

65 See UNCTAD, supra note 51, at 71-94; José, E. Alvarez The Once and Future Foreign Investment Regime , in Looking to the Future: Essays on International Law in Honor of W. Michael Reisman (Mahnoush, Arsanjani Jacob, Katz Cogan Robert, D. Sloane & Siegfried, Wiessner eds., forthcoming 2010).Google Scholar

66 Ginsburg, supra note 27, at 659-68.

67 On debates over whether Argentina is attempting to ignore awards relating to its 2000 -2001 financial crisis and, if so, what the consequences will be, see generally van Aaken, supra note 48, at 533-34; Osvaldo, J. Marzorati Argentina Opting Out? Transnat’l Dlsp. Mgmt., 2005.Google Scholar For relevant case law, see Sempra Energy Int’l v. Argentina, ICSID No. ARB/02/16, Continued Stay of Enforcement (Mar. 5, 2009) (including discussion of other relevant cases), and id., Termination of Stay of Enforcement (Aug. 7, 2009).

68 Van Aaken, supra note 48, at 536 (preferring state-state interpretive mechanisms, like the NAFTA FTC, to full renegotiation because they are less costly and more subtle).

69 See text at notes 76-91 infra.

70 See, e.g., Laurence, R. Heifer & Anne-Marie, Slaughter Towarda Theory of Effective Supranational Adjudication , 107 Yale L.J. 273, 323–26, 370-73 (1997)Google Scholar (encouraging judicial cross-fertilization and dialogue); Claire, L’Heureux-Dubé The Importance of Dialogue: Globalization and the International Impact of the Rehnquist Court , 34 Tulsa L. J. 15, 17 (1998)Google Scholar (national courts are engaging in “cross-pollination and dialogue,” fostering “mutual respect and dialogue . . . among appellate courts” by building on each other’s opinions); Anne-Marie, Slaughter A Global Community of Courts , 44 Harv. Int’l L. J. 191, 193 (2003)Google Scholar (national courts are engaging in an active and ongoing dialogue with their foreign counterparts, citing each other’s decisions as persuasive authorities rather than binding precedents); Anne-Marie, Slaughter A Typology of Transjudicial Communication , 29 U. Rich. L. Rev. 99, 103–12 (1994)Google Scholar (discussing horizontal dialogue between national courts and vertical dialogue between international and national courts) [hereinafter Slaughter, Typology].

71 See, e.g., Nico, Krisch The Open Architecture of European Human Rights Law , 71 Mod. L. Rev. 183 (2008)Google Scholar (describing dialogue between the European Human Rights Court and national courts of treaty parties); Jenny, S. Martinez Towards an International Judicial System , 56 Stan. L. Rev. 429, 430, 466 (2003)Google Scholar (“dialogue may occur among international courts, between international and national courts, national governments, and international organizations, and among national courts”); Slaughter, Typology, supra note 70, at 100-01, 106-11, 123 (describing dialogue between the European Court of Justice and national courts of treaty parties); cf Robert, B. Ahdieh Between Dialogue and Decree: International Review of National Courts , 79 N.Y.U. L. Rev. 2029 (2004)Google Scholar (arguing that investment treaty tribunal review of national court decisions exists somewhere between dialogue and decree).

72 See, e.g., Richard, Clayton Judicial Deference and”Democratic Dialogue”: The Legitimacy of Judicial Intervention Under the Human Rights Act 1998 , 2004 Pub. L. 33 Google Scholar; Tom, R. Hickman Constitutional Dialogue, Constitutional The ones and the Human Rights Act 1998 , 2005 Pub. L. 306 Google Scholar; Peter, W. Hogg & Allison, A. Bushell The Charter Dialogue Between Courts and Legislatures (Or Perhaps the Charter of Rights Isn’t Such A Bad Thing After All) , 35 Osgoode Hall L.J. 75, 79 (1997)Google Scholar (because judicial decisions based on Canada’s Charter of Fundamental Rights and Freedoms are “open to legislative reversal, modification, or avoidance, then it is meaningful to regard the relationship between the Court and the competent legislative body as a dialogue”); Symposium, Charter Dialogue: Ten Years Later , 45 Osgoode Hall L.J. 1 (2007)Google Scholar; see also Stephen, Gardbaum The New Commonwealth Model of Constitutionalism , 49 Am. J. Comp. L. 707 (2001)Google Scholar; George, Williams The Constitutional Role of the Courts: A Perspective from a Nation Without a Bill of Rights, 2 N.Z. J. Pub. & Int’l L. 25 (2004).Google Scholar

73 Critics of the legitimacy of tribunal lawmaking may take some comfort in the fact that the tribunals’ interpretive powers are somewhat constrained by treaty party practices and interpretations. Those concerned that treaty parties might abuse their interpretive powers in ongoing investor-state disputes may be relieved by the ability of tribunals to evaluate, not just rubber-stamp, treaty party interpretations. Cf Hogg & Bushell, supra note 72, paras. 5, 8 (noting that in Canada dialogue between the legislature and the courts over the Charter of Fundamental Rights and Freedoms is used to help answer criticisms that judicial review of legislation under the Charter is illegitimate because it is undemocratic).

74 Methanex v. United States, Jurisdiction and Merits, pt. IV, ch. C, para. 22 (NAFTA Ch. 11/UNCITRAL Arb. Trib. Aug. 3, 2005), available at http://www.state.g0v/s/l/c3741.htm [hereinafter Methanex Final Award]. Similarly, Brower (a very prominent arbitrator) and Schill note that states sometimes react negatively to decisions and subsequently modify their actual and model BITs to make certain provisions more explicit, as occurred with the 2004 U.S. model BIT. “Such reactions by states should, however, not be read as casting doubt on the legitimacy of the entire system of investment-treaty protection and arbitration,” they conclude. “They are rather part of a dynamic that we can equally witness in the domestic realm in the interaction between the judiciary and the legislature. . . . [T]he legislature may’correct’developments in the jurisprudence that it did not foresee or with which it does not agree.” Brower & Schill, supra note 25, at 495-96.

75 According to Caron, supra note 13, at 410-13, different actors within the system (including the parties and the adjudicators) will interact “within and against the bounded strategic space,” seeking to influence particular interpretations of the law within the space and to enlarge their influence against the space.

76 To date, there has been very little analysis of the system of international arbitration, either commercial or investment, or the strategies arbitrators, tribunals, and states within the system might employ. See generally Yves, Dezalay & Bryant, G. Garth Dealing in Virtue: International Commercial Arbitration and the Construction of A Transnational Legal Order (1996)Google Scholar; Walter, Mattli Private justice in a Global Economy: From Litigation to Arbitration , 55 Int’l Org. 919 (2001)Google Scholar. Significant growth in this theoretical, empirical, and sociological research and analysis is likely in the coming years. For early examples of empirical analyses in the context of claims about bias, see Susan, D. Franck Development and Outcomes of Investment Treaty Arbitration , 50 Harv. Int’l L.J. 435 (2009)Google Scholar; Michael, Waibel Are Arbitrators Political? (working paper presented at panel of Brit. Inst, of Int’l & Comp. Law, 2009)Google Scholar. For an early work employing theories about judicial politics in investment arbitration, see David Scnneidetman, Judicial Politics and International Investment Arbitration: Seeking an Explanation for Conflicting Outcomes , Nw. J. Int’l L. & Bus. (forthcoming 2010)Google Scholar.

77 For example, novices cannot quickly orient themselves in the field by applying a hierarchical filter, similarly to how one looks at the decisions of the top appellate courts in a particular domestic system. This problem has been ameliorated somewhat by the recent spate of good textbooks, Internet sites, and e-mail discussion lists and reporting services in the field.

78 For example, one could theorize that if a particular interpretation of a vague provision contravened the interests of the treaty parties, they could respond by revising or clarifying that provision in their next negotiations. But this reaction would assume awareness of the interpretation, the understanding that it was against their interests, and the ability to respond. As many states do not have a staff tracking these cases, or the funds to respond by intervening in cases or issuing interpretations, their silence or resort to old formulations in new treaties cannot necessarily be equated with approval.

79 See supra text at notes 6 4 - 6 5 .

80 For early discussions of the impact of the global financial crisis on potential investment treaty cases, see Jansen Calamita, N. The British Bank Nationalizations: An International Law Perspective , 58 Int’l & Comp. L.Q. 119 (2009)CrossRefGoogle Scholar; Anne van, Aaken & Jürgen, Kurtz The Global Financial Crisis: Will State Emergency Measures Trigger International Investment Disputes’. Colum. Fdi Persp., No. 3 (Vale Columbia Center on Sustainable International Investment), Mar. 23, 2009, at http://vcc.columbia.edu/pubs/ Google Scholar; see also Alvarez & Park, supra note 10, at 393-400 (discussing the bringing of investment treaty arbitration cases against developed countries as respondents); William, S. Dodge Investor-State Dispute Settlement Between Developed Countries: Reflections on the Australia—United States Free Trade Agreement , 39 Vand. J. Transnat’l L. 1 (2006).Google Scholar

81 In 2007 foreign direct investment inflows and outflows for developed states stood at $ 1248 billion and $ 1692 billion, respectively, while inflows and outflows for the developing states were $ 500 billion and $253 billion, respectively. Unctad, World Investment Report 2008, at 7 - 8 (2008).

82 By the end of 2007, 27 percent of the total number of bilateral investment treaties were between developing states, and many had been signed in recent years. Id. at 16. See generally A. Vaughan, Lowe Changing Dimensions of International Investment Law, in 1 Collected Courses of the Xiamen Academy of International Law 395 (Wenhua, Shan Penelope, Simons & Dalvinder, Singh eds., 2008).Google Scholar

83 Alvarez likens the position of countries that are major capital importers and exporters, like the United States and China, to that of the individual in John Rawls’s original position who must decide upon a distribution of resources while under a veil of ignorance. Analogously to Rawls’s thought experiment, such countries are arguably more likely to seek treaty provisions that are fair to both investors and states, as they do not know whether they will end up on the home or host state side of an investor-state dispute. Alvarez, supra note 65. Tensions between different domestic constituencies within the United States were starkly evident in the recent report, along with numerous separate statements, on whether and how to review the 2004 U.S. model Bit. Report of the Advisory Committee on International Economic Policy Regarding the Model Bilateral Investment Treaty (Sept. 30, 2009) [hereinafter Report of the Advisory Committee], available at http://www.ipsdc.org/globaleconomy/reports?start=4.

84 Compare, for example, the efforts of the United States (traditionally a strong proponent of investor rights and investor-state arbitration) to revise its model BIT to provide for greater constraints on investor rights and the discretion of investor-state tribunals, with actions by China (traditionally hostile to extensive investor protections and wide-ranging investor-state arbitration) to revise its approach to investment treaties to expand the possibilities for investor rights and investor-state arbitration. See Norah, Gallagher & Wenhua, Shan Chinese Investment Treaties: Policies and Practice (2009)Google Scholar; Alvarez, supra note 65; Cai, Congyan China-US BIT Negotiations and the Future of Investment Treaty Regime: A Grand Bilateral Bargain with Multilateral Implications , 12 J. Int’l Econ. L. 457 (2009)Google Scholar; Gilbert, Gagné & Jean-Frédéric, Morin The Evolving American Policy on Investment Protection: Evidence from Recent FTAs and the 2004 Model BIT , 9 J. Int’l Econ. L. 357 (2006)Google Scholar; Stephan, W. Schill Tearing down the Great Wall: The New Generation Investment Treaties of the People’s Republic of China , 15 Cardozo J. Int’l & Comp. L. 73 (2007)Google Scholar; Kenneth, J. Vandevelde A Comparison of the 2004 and 1994 U.S. Model BITs: Rebalancing Investor and Host Country Interests , 2008-09 Y.B. Int’l Investment L. & Pol’y 283 Google Scholar; Stephen, Schwebel The United States 2004 Model Bilateral Investment Treaty: An Exercise in the Regressive Development of International Law , Transnat’l Dlsp. Mgmt., Apr. 2006.Google Scholar

85 On the meaning of strategic action within judicial politics, see generally Lee Epstein 8c Jack, Knight Toward a Strategic Revolution in Judicial Politics: A Look Back, A Look Ahead , 53 Pol. Res. Q. 625, 626 (2000)Google Scholar (according to the strategic account: (1) judges make choices to achieve certain goals; (2) judges act strategically in the sense that their choices depend on their expectations about the choices of other actors; and (3) these choices are structured by the institutional setting in which they are made); Schneiderman, supra note 76.

86 There is no standing investment treaty court, so there is no single body to analyze. Judges on international courts routinely change, but they are appointed for multiple years in overlapping intervals, which allows for some consistency in approach to develop and become observable. There are no full-time investment law arbitrators, akin to tenured international judges. The treaty parties have control over some arbitral appointments, but not others. Certain individuals are repeatedly asked to serve as arbitrators, while others may participate in one or two cases only.

87 Recognizing these strategic motivations is not the same as claiming actual or apparent bias in favor of investors or states, as the system’s continuation depends on striking a balance between providing incentives for investor claimants to bring cases and giving comfort to state respondents considering whether to remain within the system.

88 The emphasis is on the continuation of the system and the formation of future tribunals because a state cannot unilaterally withdraw its consent to arbitrate, or disband an arbitral tribunal, after an investor has accepted its offer to arbitrate. See, e.g., ICSID Convention, supra note 16, Art. 25(1); cf.Csion, supra note 13, at 414-16 (adjudicators have an interest in being retained as an adjudicator, which means they seek to maintain or increase their personal reputation; secretariats have an interest in the continuation of the institution, so they seek to promote the institution and defend its reputation and integrity).

89 For example, Van Harten notes that because arbitrators are not tenured, they are dependent on the lodging of future claims by investors if there is to be continuing work for them in the field. He contends that this circumstance results in an appearance of proinvestor bias because it is in the arbitrators’ interests to rule broadly on jurisdictional issues and favorably to investors on merits and damages to increase the likelihood of future claims. Van Harten, supra note 11, at 172. For an interesting account of strategic considerations made by the arbitrators in the Laewen case, see the discussion of an interview with the U.S.-appointed arbitrator (Abner Mikva) in Schneiderman, supra note 76.

90 Brower & Schill, supra note 25, at 489 - 95 (arguing that there are many formal and informal mechanisms to ensure that arbitrators are independent and impartial, including arbitrators’ self-interest); Susan, D. Franck The Role of International Arbitrators , 12 Ilsaj. Int’l & Comp. L. 499, 516–18 (2006)Google Scholar (analyzing various market forces that may make it possible to remedy arbitrator misconduct and provide guidance as to the appropriate role of international arbitrators). See also empirical evaluations of arbitrator bias, supra note 76.

91 Cf. Hirschman, supra note 56, at 83-86.

92 The International Law Commission (ILC) considered, but decided against, including a specific provision in the draft Vienna Convention about treaties that created individual rights. See Report of the International Law Commission on the Work of Its Eighteenth Session, para. 33, [1966] 2 Y.B. Int’I L. Comm’n 172, 177, UN Doc. A/CN.4/SER.A/1966/Add.l [hereinafter 1966 ILC Report].

93 The interpretive rules in Article 31 of the Vienna Convention are generally accepted as reflecting customary international law. See Avena (Mex. v. U.S.), 2004ICJ REP. 12, 37-38, para. 83 (Mar. 31); Golder v. United Kingdom, 18 Eur. Ct. H.R. (ser. A), para. 29 (1975). Decisions of the Court are available at http://www.echr.coe.int.

94 Vienna Convention, supra note 2, Art. 31(3)(a), (b). On subparagraph (c) of Article 31(3), see supra note 2. See generally Campbell, McLachlan The Principle of Systemic Integration and Article 31 (3)(c) of the Vienna Convention, 54 Int’l & Comp. L.Q. 279 (2005)Google Scholar; McLachlan, supra note 53.

95 See Treaties over Time in Particular: Subsequent Agreement and Practice, in ILC, Report on the Work of Its Sixtieth Session, Annex A, UN GAOR, 63d Sess., Supp. No. 10, UN Doc. A/63/10 (2008); Treaties over Time, in ILC, Report on the Work of Its Sixty-first Session, UN GAOR, 64th Sess., Supp. No. 10, at 353, UN Doc. A/64/10 (2009). For a recent example of scholarship on subsequent practice in the trade sphere, see Alexander, M. Feldman Evolving Treaty Obligations: A ProposalforAnalyzing Subsequent Practice Derivedfrom WTO Dispute Settlement , 41 N.Y.U. J. Int’l L. & Pol. 655 (2009)Google Scholar.

96 Richard, K. Gardiner Treaty Interpretation 216-20 (2008)Google Scholar.

97 For example, Mustafa Yasseen, who was chairman of the Drafting Committee for the Vienna Convention, later wrote: “It is above all not necessary that an interpretive agreement be clothed with the same form as that of the treaty it concerns, however solemn and important this treaty may be. The interpretive agreement may be in simplified form, may be realized by an exchange of notes or even by concordant oral declarations.” Mustafa, Yasseen L’interprétation des traités d’aprés la Convention de Vienne , 151 Recueil Des Cours 1, 45 (1976 III)Google Scholar, trans. & quoted in United States, Post-Hearing Submission of Respondent 4 (July 20, 2001), Methanex Final Award, supra note 74; see also Kasikili/Sedudu Island (Bots./Namib.), 1999 ICJ Rep. 1045, para. 63 (Dec. 13).

98 Gardiner, supra note 96, at 219, 222.

99 Appellate Body Report, Japan—Taxes on Alcoholic Beverages, at 12-13, WT/DS8/AB/R, WT/DS10/ AB/R, WT/DS11/AB/R (adopted Nov. 1, 1996)Google Scholar (quoting, 1st quote, Ian Sinclair, the Vienna Convention on the Law of Treaties 137 (2d ed. 1984))Google Scholar; see also Gardiner, supra note 96, at 225; Arnold, D. Mcnair The Law of Treaties 424 (1961)Google Scholar.

100 Gardiner, supra note 96, at 228.

101 Id at 239; McNair, supra note 99, at 427 (observing that “when one party in some public document such as a statute adopts a particular meaning, circumstances can arisef,] particularly after the lapse of time without any protest from the other party, in which that evidence will influence a tribunal”).

102 1966 ILC Report, supra note 92, at 222, para. 15 (wording designed to “avoid any possible misconception that every party must individually have engaged in the practice where it suffices that it should have accepted the practice”); Gardiner, supra note 96, at 227, 235-39; Marke. Vllliger, Commentary on the 1969 Vienna Convention on the Law of Treaties 431 (2009) (requiring “active practice of some parties” that has been “acquiesced in by the other parties; and no other party will have raised an objection”).

103 Vienna Convention, supra note 2, Art. 31 (3) (“There shall be taken into account, together with the context . . .”) (emphasis added). Unlike a treaty’s negotiating history, this evidence is not a subsidiary means of interpretation relevant only to confirming existing interpretations or resolving ambiguous or obscure provisions. Id, Art. 32. Such agreements play a primary role in interpretation, in the same way as side agreements made in connection with the treaty’s conclusion. Id, Art. 31(2); Gardiner, supra note 96, at 204-08.

104 Kasikili/Sedudu Island, supra note 97, at 1075-76, para. 49 (quoting 1966 ILC Report, supra note 92, at 221-22, paras. 14-15 (emphasis added)).

105 On bindingness, see, for example, Gardiner, supra note 96, at 32 (“That the agreement of the parties on an interpretation trumps other possible meanings seems obvious enough, given the nature of a treaty as an international agreement between its parties.”); Oppenheim, supra note 38, at 1268, para. 630; Vllliger, supra note 102, at 429. On persuasiveness, see, for example, Interpretation of the Air Transport Services Agreement of 6 February 1948 (Italy v. U.S.), 16 R. Int’l Arb. Awards [RIAA] 75, 99 (1965) [hereinafter Italy-U.S. Award] (noting that the subsequent practice of treaty parties is not “in itself decisive for the interpretation of the disputed text; it can however serve as additional evidence as regards the meaning to be attributed to the text”); International Status of South West Africa, Advisory Opinion,1950 ICJ Rep. 126, 135-36 (July 11).

106 There is some basis for this argument in the drafting history of the Vienna Convention. The original ILC draft contained Article 38, concerning the modification of treaties by subsequent practice. The Committee of the Whole deleted the article in response to various objections, including that it would be difficult to distinguish which interpretations would fall under this provision and which under the equivalent of Article 31 (3) (b), that permitting modifications by contrary practice might undermine the principle of pacta sunt servanda, and that such modifications might lead to changes even though states had not gone through their internal constitutional procedures for approving treaties and their amendment. See 1966 ILC Report, supra note 92, at 236, para. 1; 1 UN Conference on the Law of Treaties, Official Records 207-15, UN Doc. A/CONF.39/11, UN Sales No. E.68.V.7 (1968).

107 See Access to German Minority Schools in Upper Silesia, Advisory Opinion, 1931 PCIJ (ser. A/B) No. 40, at 19 (May 15) (interpretations by courts have retrospective effect); Yasseen, supra note 97, at 47 (interpretations by treaty parties have retrospective effect).

108 Anthony, Aust Modern Treaty Law and Practice 265 (2d ed. 2007)Google Scholar (“[I]f both parties want to amend . . . a treaty, they can of course do so. . . . [S]hould [an amendment clause] not be suitable, the parties can simply ignore it and amend the treaty in any way they can agree on.”); Gardiner, supra note 96, at 243-45; Oppenheim, supra note 38, at 1254, para. 624 (“A treaty may also be amended by an oral agreement, or by a tacit agreement evidenced by the subsequent practice of the parties.”); Sinclair, supra note 99, at 138; Vllliger, supra note 102, at 429.

109 The most famous example is the interpretation of Article 27(3) of the UN Charter, which requires nonprocedural votes in the Security Council to be passed by “an affirmative vote of nine members including the concurring votes of the permanent members.” In practice, the international community has accepted that a nonprocedural vote may be passed by an affirmative vote of nine members without a veto by any permanent members. While clearly departing from the original intention and text, this interpretation was affirmed by the ICJ in Legal Consequences for States of the Continued Presence of South Africa in Namibia (South West Africa) Notwithstanding Security Council Resolution 276 (1970), Advisory Opinion, 1971 ICJ Rep. 16, 22, para. 22 (]une 21). See also, e.g., Dispute Regarding Navigational and Related Rights (Costa Rica v. Nicar.), para. 64 (Int’l Ct. Justice July 13, 2009) (“ [S] ubsequent practice . . . can result in a departure from the original intent on the basis of a tacit agreement between the parties . . . .”); Interpretation of the Air Transport Services Agreement of 27 March 1946 (Fr. v. U.S.), 16 RIAA 5, 60-68 (1963) [hereinafter U.S.-France Award] (subsequent practice under a bilateral treaty is relevant to interpretation and may amount to an amendment of the treaty); Italy-U.S. Award, supra note 105, at 99-101 (the parties’ interpretation of a treaty could be established with a shorter period of continuity than customary international law, though the situation would be different if the practice amounted to an amendment); Location of Boundary Markers in Taba (Egypt v. Israel), 20 RIAA 3 (1988).

110 Vienna Convention, supra note 2, Art. 31(1), (3), (4).

111 Villiger, supra note 102, at 429.

112 Where the parties appear to have so agreed for a period of time, through their actions or words, but one has then changed its mind, the previous agreement may work like an estoppel as to the interpretation of the agreement. See, e.g., Temple of Preah Vihear (Cambodia v. Thail.), 1962 ICJ Rep. 6, 32-33 (June 15); Legal Status of Eastern Greenland, 1933 PCIJ (ser. A/B) No. 53, at 6 8 - 6 9 (Apr. 5).

113 Air services treaties, for instance, affect whether commercial airlines may fly between countries, but they can be readily revoked or modified. See U.S.-France Award, supra note 109, at 60 - 67; Italy-U.S. Award, supra note 105, at 99-101. Similar points could be made in relation to treaties dealing with the use of force, refugees, trade, and the environment.

114 Vienna Convention, supra note 2, Art. 1; Aust, supra note 108, at 7.

115 For example, the evolutionary approach to interpreting human rights treaties can be understood as a particular application of the Vienna Convention’s object-and-purpose test, see Villiger, supra note 102, at 427-28, whereas claims that the Vienna Convention’s general approach to reservations should not be applied to human rights treaties are highly contentious. Compare Belilos v. Switzerland, 132 Eur. Ct. H.R. (ser. A), para. 60 (1988), Loizidou v. Turkey, Preliminary Objections, 310 Eur. Ct. H.R. (ser. A), paras. 96-98 (1995), and UN Human Rights Committee, General Comment No. 24 (52), UN Doc. CCPR/C/21/Rev.l/Add.6 (1994), with ILC, Preliminary Conclusions on Reservations to Normative Multilateral Treaties Including Human Rights Treaties, in Report on the Work of Its Forty-ninth Session 56, UN GAOR, 52d Sess., Supp. No. 10, UN Doc. A/52/10 (1997), Observations on General Comment No. 24 (52), in Report of the Human Rights Committee, Annex VI, at 131, 135, UN GAOR, 50th Sess., Supp. No. 40, UN Doc. A/50/40 (1995) (statements of the United States and the United Kingdom), and Observations of States Parties Under Article 40, Paragraph 5, of the Covenant, in Report of the Human Rights Committee, Annex VI, at 117, UN GAOR, 51st Sess., Supp. No. 40, UN Doc. A/51/40 (1996) (statement of France).

116 See text at notes 22-25 supra. Human rights and investment treaties can also create state-to-state rights and obligations, as well as opportunities for interstate dispute resolution. This article does not consider the nature of these rights or dispute resolution mechanisms, or whether they exist independendy of or interdependently with the substantive and procedural rights granted to nonstate actors.

117 See text at notes 130-35 infra.

118 See, e.g.,Golder, supra note 93, para. 29; Bankovií v. Belgium, Admissibility, 2001-XII Eur. Ct. H.R. 333, para. 55 (Grand Chamber). On the application of the Vienna Convention’s interpretive principles by the Inter- American Court and Commission of Human Rights, see “Other Treaties” Subject to the Consultative Jurisdiction of the Court (Art. 64 American Convention on Human Rights), Advisory Opinion, Inter-Am. Ct. H.R. (ser. A) No. 1, para. 33 (Sept. 24, 1982) (recognizing the applicability of the Article 31-33 principles of interpretation); Santana v. Venezuela, Case 0453/01, Inter. Am. C.H.R., Report No. 92/03, paras. 77-78, OEA/Ser.L/V/II.118 (2003) (same). The European Court’s approach on interpretations seems generally consistent with the approach of other human rights bodies, but it appears to make more extensive reference to subsequent practice than other such courts and treaty bodies. One reason may be that historically the parties to the Convention have been a relatively small group that were all established representative democracies operating within a framework of regional integration. Though now, with forty-seven treaty parties, this explanation seems less compelling.

119 See ECHR, supra note 22, Art. 36(1), (2) (the home state of the applicant may intervene as of right and the Court is empowered to permit interventions by other treaty parties and interested persons, including nongovernmental organizations).

120 See, e.g., Soering v. United Kingdom, 161 Eur. Ct. H.R. (ser. A) (1989) (intervention by the Federal Republic of Germany in support of the applicant, a German national, whose claim was successful in part); Saadi v. Italy, App. No. 37201/06 (Eur. Ct. H.R. Feb. 28, 2008) (intervention by the United Kingdom in support of Italy, whose defense was unsuccessful).

121 This sort of emerging consensus overlaps with the Court’s preference for an evolutionary approach to rights. The difference between the use of subsequent agreements and practice and evolutionary approaches to human rights treaties is controversial. See Gardiner, supra note 96, at 242-43.

122 There are clearly differences between the two examples cited below, including that one concerns a substantive right and the other a jurisdictional question. My point is not that the circumstances are equivalent but that the European Court has used subsequent practice both to widen and to narrow potential understandings of the ECHR.

123 Tyrer v. United Kingdom, 26 Eur. Ct. H.R. (ser. A), para. 31 (1978) (emphasis added). According to Ovey and White, the European Court has engaged in similar comparative surveys as a guide to the scope of the rights guaranteed in many areas, including laws relating to vagrancy, respect for family life, various aspects of criminal procedure, and the age of criminal responsibility. Clare, Ovey & Robin, White Jacobs and white: The> European Convention on Human Rights 49 (4th ed. 2006)+European+Convention+on+Human+Rights+49+(4th+ed.+2006)>Google Scholar; see also George, Letsas A Theory of Interpretation of the European Convention on Human Rights 123 (2008)Google Scholar.

124 Bankovtć, supra note 118, para. 62 (emphasis added).

125 Soering, supra note 120, para. 103.

126 Id.

127 Öcalan v. Turkey, App. No. 46221/99, para. 163 (Eur. Ct. H.R. May 12, 2005) (Grand Chamber) (quoting id., Chamber judgment of Mar. 12, 2003, para. 191).

128 Controversially, in Öcalan, the Court considered (but did not ultimately decide) whether the practice of the vast majority of member states with respect to the death penalty might de facto amend the ECHR with respect to all of the member states, including those that had not yet signed or ratified the relevant protocol. Id., paras. 163- 65.

129 Cruz Varasv. Sweden, 201 Eur. Ct. H.R. (ser.A),para. 100(1991) (“Subsequent practice could be taken as establishing the agreement of Contracting States regarding the interpretation of a Convention provision but not to create new rights and obligations which were not included in the Convention at the outset.”) (citations omitted).

130 In drawing this structural analogy, I am not arguing that the two regimes are substantively similar or structurally identical, or that human rights norms should be applied in the investment context. On the relationship between human rights and investment treaties, see generally Human Rights in International Investment Law and Arbitration, supra note 33; UNCTAD, Selected Developments in IIA Arbitration and Human Rights, IIA Monitor No. 2, 2009. On the limits of substantive human rights analogies, see Van Harten, supra note 11, at 136-41.

131 Anthea Elizabeth Roberts, Traditional and Modem Approaches to Customary International Law, 95 AJIL757, 764-66 (2001).

132 The European Court’s approach to the excesses of certain antiterrorist legislation since September 11, 2001, is an example of this approach. See Saadi, supra note 120.

133 For example, members of the European Union and the Council of Europe are expected to be or become parties to the ECHR, making the consequences of withdrawal from the ECHR dramatic. See Stone Sweet & Grisel, supra note 33, at 122 (the ECHR’s amendment provisions make the Court’s zone of discretion wider than that of many domestic constitutional courts).

134 Differences between the backgrounds of people appointed to the European Court and investment tribunals, and their methods of appointment, may also influence their interpretive approaches. The Court is a permanent body made up of judges, usually with a human rights background, elected by the treaty parties for set terms. Permanency should help to establish and protect these judges’ independence, though their public international law backgrounds and the appointment process arguably make them more considerate of treaty party views. Arbitrators on investment tribunals are not selected solely by the treaty parties and many have a background primarily in international commercial arbitration rather than public international law. These factors may make these arbitrators less familiar with or concerned about public international law interpretive approaches, such as the relevance of subsequent agreements and practices of treaty parties. On arbitrators’ backgrounds, see Schneiderman, supra note 76.

135 Conversely, finding a subsequent agreement or common practice should be easier in a bilateral investment treaty context, while the proportional weight of the respondent state’s practice will be greater, which might make tribunals more cautious about relying on such evidence.

136 Aust, supra note 108, at 7. A recent study of ICSID decisions found references to Articles 31-33 of the Vienna Convention in thirty-five of ninety-eight decisions. Fauchald, supra note 1, at 314.

137 Some treaties, like NAFTA, provide that interpretations issued by such an interpretive body “shall be binding” on investment tribunals. See, e.g., NAFTA, supra note 3, Art. 1131 (2); United States, Treaty Concerning the Encouragement and Reciprocal Protection of Investment, Art. 30(3) (2004), available at http://www.state.gov/documents/organization/117601.pdf [hereinafter 2004 U.S. Model BIT]; Canada, Agreement for the Promotion and Protection of Investments, Arts. 40(2), 51 (2004), available at http://ita.law.uvic.ca/ [hereinafter 2004 Canada Model BIT]. Some treaties seek to prevent tribunals from deciding whether an agreement represents a permissible interpretation or an impermissible amendment. See 2004 U.S. Model BIT, An. 30(3) (“A joint decision of the Parties. . .declaring their interpretation of a provision of this Treaty shall be binding on a tribunal.. . .”). This wording seems intended to circumvent the controversial Pope & Talbot decision that, even though interpretations issued by the FTC are binding, tribunals have the power to determine whether an alleged interpretation is really an amendment. Compare Pope & Talbot Damages, supra note 6, para. 47, quoted in note 6 supra, with ADF Group, supra note 8, para. 177, quoted in text at note 9 supra.

138 For example, the now-shelved 2007 draft Norwegian model BIT proposed creating a joint committee (similar to the NAFTA FTC) that could (1) amend the treaty, subject to ratification, acceptance, or approval by the parties; and (2) issue interpretations, subject to the need to (a) bear in mind that the power should not be used to undermine the amendment provisions, and (b) refrain from adopting interpretations of provisions subject to existing investor-state arbitrations. See Norway, Agreement for the Promotion and Protection of Investments, Arts. 14(2), 23(4), 33(1) (2007), available at http://ita.law.uvic.ca/; see also Damon, Vis-Dunbar Norway Shelves Its Proposed Model Bilateral Investment Treaty, Investment Treaty News, June 2009, at 7.Google Scholar

139 See Methanex Final Award, supra note 74, pt. IV, ch. C, para. 20 (finding that the power of the FTC to issue binding interpretations was “clear beyond peradventure (and any investor contemplating an investment in reliance on NAFTA must be deemed to be aware of it)”). Consider also, by analogy, the Channel Tunnel arbitration, where the treaty provided that the states and concessionaires could appoint arbitrators, but the “arbitrators appointed by the Concessionaires shall not participate in that part of any decision relating to the interpretation or application of die Treaty.” Channel Tunnel Group Ltd. v. France, Partial Award on Jurisdiction, para. 76 (Perm. Ct. Arb. Jan. 30, 2007) (emphasis omitted), Oxford Rep. Int’l Inv. Claims, No. 58 (2007). After a dispute arose, the concessionaires argued that a narrow interpretation of this provision was “warranted on grounds of equality of arms” because “it cannot seriously be envisaged that the Parties would have elaborated a dispute resolution mechanism excluding the Concessionaires’ arbitrators from decisions having a direct impact on the Concessionaires.” Id., para. 81 (quoting, 2d quote, from claimants’ submission on an article of the treaty). In rejecting this argument, the tribunal found that the concessionaires took their treaty rights subject to other treaty provisions, including that their appointed arbitrators could not participate in decisions on interpretation or application of the treaty. Id, paras. 86-90.

140 See, e.g., NAFTA, supra note 3, Art. 1131(1); 2004 U.S. Model BIT, supra note 137, Art. 30(1); 2004 Canada Model BIT, supra note 137, Art. 40(1).

141 See, e.g., NAFTA, supra note 3, Art. 1128; 2004 U.S. Model BIT, supra note 137, Art. 28(2); 2004 Canada Model BIT, supra note 137, Art. 35.

142 See, e.g., 2004 U.S. Model BIT, supra note 137, Art. 37(1); United Kingdom, Agreement for the Promotion and Protection of Investments, Model Text 2005, Art. 9, as amended’(2006), reprinted in Campbell, McLachlan Laurence, Shore & Matthew, Weiniger International Investment Arbitration: Substantive Principles 379 (2007)Google Scholar; India, Agreement for the Promotion and Protection of Investments, Art. 10 (2003), available at http://ita.law.uvic.ca/ Google Scholar; France, Draft Agreement on the Reciprocal Promotion and Protection of Investments, Art. 10 (2006), available at http://ita.law.uvic.ca/ Google Scholar; Germany, Treaty Concerning the Encouragement and Reciprocal Protection of Investments, Art. 9 (2008), available at http://ita.law.uvic.ca/ Google Scholar; Sri Lanka, Agreement for the Promotion and Protection of Investments, Art. 9 Google Scholar, reprinted in Mclachlan, Shore, & Weiniger, supra, at 427.

143 If treaty parties are allowed to reduce the scope of investor rights through amendment and withdrawal, why not through interpretation? Some might argue that, by analogy with human rights treaties, restrictive interpretations are impermissible, as contrary to the object and purpose of promoting investment. But the normative nature of human rights and investment obligations differs, rendering this substantive analogy questionable, and strong arguments exist that the object and purpose of investment treaties is both broader and more balanced than simply promoting investment. See Dolzer & Schreuer, supra note 11, at 32-33; Douglas, Investment Claims, supra note 19, at 84-85, para. 150; Van Harten, supra note 11, at 136-41. Compare SGS Société Générale de Surveillance S.A. v. Philippines, ICSID No. ARB/02/6, Jurisdiction, para. 116 (Jan. 29, 2004) (it is legitimate to resolve uncertainties in favor of protecting investors because the object and purpose of investment treaties is to promote and protect investment), with Saluka Invs. B.V. v. Czech Republic, Partial Award, para. 300 (UNCITRALArb. Trib. Mar. 17, 2006), available at http://ita.law.uvic.ca/ [hereinafter Saluka Partial Award] (a balanced approach to interpretation is required because protecting foreign investments is not the sole aim of investment treaties but, rather, is a necessary element alongside the overall aim of encouraging investment).

144 It is beyond the scope of this article to set out the various factors that could or should be considered in establishing what amounts to a “reasonable” interpretation. As a starting point, the reasonableness of an interpretation is usually judged according to the other interpretive factors set out in Articles 31-33 of the Vienna Convention. Importantly, this article assumes that there may be more than one reasonable interpretation of a provision.

145 For the impact of timing, see text at notes 155-66 infra.

146 This argument was made by some who criticized the FTC’s Notes of Interpretation as an impermissible amendment. See, e.g., Alvarez & Park, supra note 10; Brower II, Empire Strikes Back, supra note 10; Brower II, FTC Notes, supra note 10; Park, supra note 10.

147 See Methanex Final Award, supra note 74, pt. IV, ch. C, paras. 20-21 (“Methanex cites no authority for its argument that far-reaching changes in a treaty must be accomplished only by formal amendment rather than by some form of agreement between all of the parties.. . . Article 39 of the Vienna Convention on the Law of Treaties says simply that ’[a] treaty may be amended by agreement between the parties’. No particular mode of amendment is required and many treaties provide for their amendment by agreement without requiring a re-ratification.”); text at notes 108 - 09 supra. Investment treaties do not contain any provisions that appear to give investors a procedural right to have their substantive rights amended according to a particular process only.

148 As a general rule, a treaty may be terminated or one party may withdraw in conformity with the provisions of the treaty or at any time by consent of all of the treaty parties, and the treaty parties may amend the treaty, either according to the treaty’s terms or simply by agreement. See Vienna Convention, supra note 2, Arts. 39, 54. Many investment treaties contain provisions on termination, withdrawal, duration, and amendment.

149 See, for the United States, 17A Am. Jur. 2D Contracts §§450-51 (2009) (acceptance and reliance); Restatement (Second) of Contracts §311(1981) (same); for England, Contracts (Rights of Third Parties) Act, 1999, c. 31 (acceptance and reliance); for various civil law systems, Commentary on the Unidroit Principles of International Commercial Contracts, Art. 5.2.5, at 604 (Jan Kleinheisterkamp & Stefan Vogenauer eds., 2009) (discussing acceptance under these systems).

150 Vienna Convention, supra note 2, Art. 37(2); see also 1966 ILC Report, supra note 92, at 230, para. 4 (this formulation was intended to balance two interests: that states not be “discouraged from creating rights in favour of third States . . . by the fear that they might be hampering their freedom of action in the future,” and that those rights have “a measure of solidity and firmness”). On whether these or analogous rights might be subject to other limiting doctrines, such as estoppel, legitimate expectations, or good faith, see text at notes 160-66 infra.

151 See Vllliger, supra note 102, at 495 (“[Article 37(2)] stipulates a presumption in favour of revocation or modification without consent of the third State.”). This provision also establishes the opposite presumption to that created by treaties that confer obligations on third parties, where it is presumed that the third party must consent to changes unless the contrary intention is established. See Vienna Convention, supra note 2, Art. 37(1); Christine, Chinkin Third Parties in International Law 34, 42 (1993)Google Scholar.

152 This conclusion is consistent with domestic law: the law may grant rights to particular persons, but that does not prevent the legislature from changing the law subsequently. For example, a tax code may set out certain tax advantages for selling investment properties and a buyer may purchase an investment property in the hope of selling that property, with those tax advantages, at a later date. The buyer’s reliance would not prevent the tax code from being changed subsequendy to revoke those tax advantages, as the buyer acted with knowledge that the tax laws might change before his or her right was crystallized. But the analysis may be different if the right had already been crystallized, for example, by the buyer’s having sold the property prior to the change in the law. See generally Ben Juratowitch, Retroactivity and the Common Law l—13 (2008).

153 See supra text at notes 108-09.

154 In re Jaworzina (Polish-Czechoslovakian Frontier), Advisory Opinion, 1923 PCIJ (ser. B) No. 8, at 37 (Dec. 6) (“ [ I ] t is an established principle that the right of giving an authoritative interpretation of a legal rule belongs solely to the person or body who has power to modify or suppress it.”); Sinclair, supra note 99, at 136.

155 In practice, this means that de facto amendments may be more likely to be accepted on the basis of a subsequent agreement of the parties than on subsequent practice alone. Cf. text at notes 106-09 supra.

156 For example, many investment treaties impose a notice period on termination and withdrawal (often one year), provide that their substantive provisions continue beyond termination or withdrawal for a certain period after an investment was made (often ten to twenty years), and require amendments to take effect after a time lag (often ninety days). UNCTAD, Bilateral Investment Treaties 1995-2006: Trends in Investment Rulemaking 20-21 (2007).

157 Dolzer & Schreuer, supra note 11, at 38-45; Douglas, Investment Claims, supra note 19, at 328-43.

158 See supra note 107.

159 See Vienna Convention, supra note 2, Art. 28; Villiger, supra note 102, at 384. This presumption would probably apply only where the amending interpretation serves to diminish rather than enhance the investor’s rights. The presumption against retroactivity in many domestic laws is more easily overcome where the change in law is to the advantage of an individual. See Juratowitch, supra note 152, at 115-18, 195-97, 223-24. This is consistent with the approach taken to nonretroactivity of criminal laws in the human rights field. See, e.g., International Covenant on Civil and Political Rights, Art. 15(l),Dec. 16, 1966,999 UNTS 171;ECHR,supra note22,Art.7(l).

160 See Oppenheim, supra note 38, at 1263, para. 626.

161 See Brownlie, supra note 38, at 153, 643-44 (setting out a test for estoppel but also warning that “estoppel in municipal law is regarded with great caution, and that the ’principle’ has no particular coherence in international law”); Malcom, N. Shaw International Law 102-03, 517–19 (6th ed. 2008).Google Scholar On estoppel in investment treaty law generally, see Newcombe & Paradell, supra note 11, at 526-28, §10.27.

162 See Temple of Preah Vihear, supra note 112, at 32-33; Pope & Talbot Inc. v. Canada, supra note 6, Interim Award, para. I l l (June 26, 2000), available at http://ita.law.uvic.ca/ (citing Bowett, D. W. Estoppel Before International Tribunals and Its Relation to Acquiescence, 1957 Brit. Y.B. Int’ll. 176, 202 Google Scholar).

163 On legitimate expectations in investment treaty law generally, see Dolzer & Schreuer, supra note 11, at 133-40; Newcombe & Paradell, supra note 11, at 279-89, §6.26.

164 See, e.g., Paul, Craig EU Administrative Law 635-37 Google Scholar (16 Collected Courses of the Academy of European Law, bk. 1, 2006) (citing a European Court of Justice case to the effect that” [w] hilst the protection of legitimate expectations is one of the fundamental principles of the Community, economic operators cannot have a legitimate expectation that an existing situation which is capable of being altered by the Community institutions in the exercise of their discretion will be maintained,” Case C-402/98, ATB v. Ministero per le Politiche Agricole, 2000 ECR 1-5501); SØren, J. SchØnberg Legitimate Expectations in Administrative Law (2000)Google Scholar.

165 Compare Saluka Partial Award, supra note 143, para. 305 (“No investor may reasonably expect that the circumstances prevailing at the time the investment is made remain totally unchanged.”), with Occidental Exploration & Prod. Co. v. Ecuador, paras. 190-91 (London Ct. Int’l Arb. July 1, 2004), available at http://ita.law.uvic.ca/, and Técnicas Medioambientales Teemed, S.A. v. Mexico, ICSID No. ARB(AF)/00/2, para. 154 (May 29, 2003), 43 ILM 133 (2004) [hereinafter Teemed Award].

166 See oppenheim, supra note 38, at 38, para. 12 n.7.

167 Fauchald, supra note 1, at 333. On attempts to reach interpretive agreements under other treaties, see Nat’l Grid PLC v. Argentina, Jurisdiction, para. 85 (UNCITRAL June 20, 2006), available at http://ita.law.uvic.ca/ (noting that, “after the decision on jurisdiction in Siemens [A.G. v. Argentina, ICSID No. ARB/02/8, Jurisdiction (Aug. 3, 2004), 44 ILM 138 (2005)], the Argentine Republic and Panama exchanged diplomatic notes with an ’interpretative declaration’ of the [most-favored-nation] clause in their 1996 investment treaty to the effect that, the MFN clause does not extend to dispute resolution clauses, and that this has always been their intention”); William W. Burke-White, The Argentine Financial Crisis: State Liability Under BITs and the Legitimacy of the ICSID System, in Backlash, supra note 59, at 407, 431 (“senior officials in the Argentine government have indicated a desire to reach an agreement with the U.S. publicly clarifying the self-judging nature” of a particular clause in the U.S.-Argentine BIT (citing a statement by Osvaldo, Guglielmino, then procurador del tesoro de la nación argentina, American Univ. Washington College of Law, Oct. 24, 2007 Google Scholar)).

168 See, e.g., McLachlan, supra note 53, at 372.

169 See text at notes 93-94 supra.

170 Despite the initial furor over the FTC’s Notes of Interpretation, most NAFTA tribunals have now accepted these interpretive directions, partly because NAFTA expressly empowered the FTC to issue binding interpretations, which put investors on notice of this interpretive power. See, e.g., Methanex Final Award, supra note 74, pt. II, ch. B, paras. 11-25, & pt. IV, ch. C, paras. 9-27; Loewen, supra note 23, paras. 125-29; ADF Group, supra note 8, paras. 175-86; Mondev Int’l Ltd. v. United States, ICSID No. ARB(AF)/99/2, paras. 99-125 (NAFTA Ch. 11 Arb. Trib. Oct. 11, 2002), 42 ILM 85 (2003). It could be argued that including such a formal mechanism operates to exclude recourse to informal agreements, but this argument must be assessed in the context of the particular treaty.

171 On bindingness, see, for example, note 137 supra. On persuasiveness, see, for example, Netherlands- Czech Republic BIT, Art. 9, Apr. 24, 1991, available at http://www.unctad.org/sections/dite/iia/docs/bits/ czech_netherlands.pdf (“Either Contracting Party may propose the other Party to consult on any matter concerning the interpretation or application of the Agreement. The other Party shall accord sympathetic consideration to and shall afford adequate opportunity for such consultation.”). In CME v. Czech Republic, the latter called for consultations with the Netherlands after the partial award was issued because of concern over certain interpretations that it believed were inconsistent with the treaty. As a result of these meetings, the two states reached “common positions” on three issues, which they recorded in Agreed Minutes. The tribunal rightly rejected the Czech Republic’s argument that these Agreed Minutes were binding on the tribunal, but it is questionable whether the tribunal gave due consideration to these agreed positions in its final award. CME Czech Republic B.V. v. Czech Republic, Final Award, paras. 87-93, 198,216-26, 437, 504 (UNCITRALMar. 14, 2003), available at http://ita.law.uvic.ca/.

172 Aguas del Tunari v. Bolivia, Respondent’s Objections to Jurisdiction, ICSID No. ARB/02/3, para. 251 (Oct. 21, 2005), 20 ICSID Rev. 450 (2005). The tribunal went on to consider whether these statements amounted to subsequent practice evidencing an agreement. Id.

173 Methanex Final Award, supra note 74, pt. II, ch. B, para. 20 (“From the ICJ’s approach in the KasikililSedudu Island case, it appears that no particular formality is required for there to be an ’agreement’ under Article 31 (3) (a) of the Vienna Convention.”).

174 See, e.g., Fauchald, supra note 1, at 332.

175 Dolzer & Schreuer, supra note 11, at 35. This concern was also expressed by the Pope & Talbot tribunal, see supra notes 6-7, and in the expert opinion of Robert Jennings of September 6, 2001, discussed in Methanex Final Award, supra note 74, pt. IV, ch. C, para. 5.

176 It is open to debate whether consideration of pleadings should be limited to pleadings by other treaty parties on the same treaty or extend to include pleadings by treaty parties relating to identical or similar provisions in other treaties. If die latter approach were adopted, one would need to be careful to consider differences in contexts that might limit die usefulness of such pleadings, in spite of the similarity of the provisions.

177 Gas Natural SDG S.A. v. Argentina, ICSID No. ARB/03/10, Jurisdiction, para. 47 n.12 (June 17, 2005), available at http://www.asil.0rg/pdfs/GasNat.v.Argentina.pdf.

178 Dolzer & Schreuer, supra note 11, at 34.

179 Enron Corp. v. Argentina, ICSID No. ARB/01/3, Jurisdiction, para. 48 (Jan. 14, 2004), available at http://ita.law.uvic.ca/ [hereinafter Enron Jurisdiction]; see also id., Jurisdiction (Ancillary Claim), para. 37 (Aug. 2, 2004) [hereinafter Enron Ancillary Claim].

180 See supra note 25.

181 Brower II, supra note 31, at 74-82.

182 For a discussion of the U.S. approach to these issues, see Barton, Legum Representing States—A US Perspective, 6 Arb. & Adr (Int’l B. Ass’n Newsletter), June 2001, at 46Google Scholar, 47 (“Government counsel.. . needs not only to identify the winning argument, but also to ensure, through detailed discussions with his or her colleagues in other interested agencies, that that argument properly balances the interests of the US Government. Our arguments must achieve the right result not only in the case at hand but also in other, hypothetical cases that might arise in the future.”); Barton Legum, The Difficulties of Conciliation in Investment Treaty Cases: A Comment on Professor Jack C. Coe’s “Toward a Complementary Use of Conciliation in Investor-State Disputes: A Preliminary Sketch, “Mealey’s Int’l Arb. REP., Apr. 2006, at 23 n.2 (in investment disputes, decisions by the U.S. government are made by an interagency group including representatives from the Departments of State, Commerce, Justice, the Interior, and the Treasury; the U.S. Trade Representative; and the state, local, or federal agency whose acts are at issue).

183 Self-interested pleadings are considered relevant evidence for interpretation in other contexts. See, e.g., International Law Association, Committee on the Formation of Customary (General) International Law, Final Report 14 (2000), available at http://www.ila-hq.org/ Google Scholar (state practice includes “pleadings before international tribunals”); Brownlie, supra note 38, at 24 (“Pleadings before the International Court contain valuable collations of material and, at the least, have value as comprehensive statements of the opinions of particular states on legal questions.”); l International Committee of the Red Cross, Customary International Humanitarian Law at xxxii (Jean-Marie, Henckaerts & Louise, Doswald-Beck eds., 2005)Google Scholar (defining state practice to include “pleadings before international tribunals”). For example, the ICRC study places weight on state pleadings in Legality of the Threat or Use of Nuclear Weapons, despite the clear self-interest of both nuclear and non-nuclear states. Id. at 148, 152, 243-49, 252-53, 258. Some states have argued for the same approach to be taken to pleadings in the investment context. See, e.g., Sean D. Murphy, Contemporary Practice of the United States, 95 AJIL 887-89 (2001) (discussing this argument by the United States in Methanex and Pope & Talbot); Enron Ancillary Claim, supra note 179, para. 34 (Argentina’s argument). But see Empresas Lucchetti, S.A., supra note 18, Annulment, Dissenting Opinion of Sir Franklin Berman, para. 9 (Aug. 13, 2007) (discussing the relevance of pleadings).

184 Self-interested statements routinely form the basis of customary international law and customary interpretations of treaty provisions. The Hull rule and Caroline test are examples par excellence of self-interested statements made in connection with a particular dispute that have been treated as relevant evidence of state practice. The Hull rule, requiring compensation for expropriation to be “full, prompt and adequate,” was named after U.S. Secretary of Sate Cordell Hull, who set out this position in correspondence with the Mexican government after Mexico nationalized U.S. oil companies in 1938. See Van Harten, supra note 11, at 91 n. 120. The Caroline test, requiring that the “necessity of. . . self-defence [be] instant, overwhelming, and leaving no choice of means, and no moment for deliberation,” was formulated in 1841 after the British destroyed the steamboat SS Caroline. Letter from Daniel Webster, U.S. secretary of state, to Henry Fox, British minister in Washington (Apr. 24, 1841), quoted in 2 John Bassett Moore, A Digest of International Law 412 (1906).

185 Whether the state’s general views were being set out could be determined, for example, by looking at how the pleadings are formulated or by the issuance by a state of a statement that its pleadings reflect its general interpretive views (which might give tribunals more reason to take notice of interpretations proffered and states greater pause in making opportunistic arguments). For example, in Sempra Energy International v. Argentina, the tribunal noted that “Counsel representing the State in arbitration proceedings have the duty to put forward all the arguments they deem appropriate to defend their position, but a tribunal could not presume that each of those arguments constitutes the expression of a unilateral act that obligates the State” in the absence of express intention to do so. Sempra Energy Int’l, supra note 67, Objections to Jurisdiction, para. 146 (May 11, 2005) [hereinafter Sempra Jurisdiction]. When pleadings are supported by other evidence of the treaty parties’ views, such as interventions and model BITs, they should be given greater weight than when they are not supported by, or conflict with, other practice. For example, in Enron v. Argentina, the tribunal stated that a relevant “decision of the United States Supreme Court should probably have more weight for the purpose of the United States’ views on indirect ownership than that expressed in arbitrations by counsel for that government.” Enron Ancillary Claim, supra note 179, para. 39 (citing Dole Food Co. v. Patrickson, 538 U.S. 468 (2003)).

186 Fauchald, supra note 1, at 348.

187 Some tribunals afford interventions significant weight, such as the ADF v. United States tribunal, which noted that die respondent state’s interpretation had been accepted by the other NAFTA treaty parties during interventions in that and other cases. See ADF Group, supra note 8, para. 179. Others have given interventions little deference, such as the Pope & Talbot tribunal, which noted the unanimous agreement of the treaty parties on a matter of interpretation, before rejecting the interpretation without any discussion of the weight to be given to these submissions. Pope & Talbot Inc. v. Canada, supra note 6, Merits of Phase 2, para. 79 (Apr. 10, 2001), available at http://ita.law.uvic.ca/.

188 See, e.g., ICSID Convention, supra note 16, Art. 27(1).

189 NAFTA, supra note 3, Art. 1128.

190 See, e.g., Schreuer & Weiniger, supra note 46, at 1201.

191 See, e.g., NAFTA, supra note 3, Art. 1128.

192 Aguas del Tunari, supra note 172, paras. 47, 249-63 (relying on ICSID Rule 34, available at ICSID Web site, supra note 8). Conscious of the prohibition in Article 27 of the ICSID Convention against provision of diplomatic protection by the home state, the tribunal emphasized that it did not “seek the view of the Netherlands as to the Tribunal’s jurisdiction” but, rather, sought “only to secure the comments of the Netherlands as to specific documentary bases” for its responses in parliament, reminding the Netherlands that it was interested in “interpretative positions of general application rather than ones related to a specific case.” Id., para. 258.

193 SGS Société Générale de Surveillance S.A. v. Pakistan, ICSID No. ARB/01/13, Jurisdiction (Aug. 6, 2003), 42 ILM 1290 (2003).

194 Note on the Interpretation of Article 11 of the Bilateral Investment Treaty Between Switzerland and Pakistan, attached to the Letter of the Swiss Secretariat for Economic Affairs to the ICSID Deputy-Secretary General (Oct. 1, 2003), reprinted in Mealey’s Int’l Arb. Rep., Feb. 2004, §E-05-040227-IIIX, quoted in Todd Weiler, International Investment Law and Arbitration: Leading Cases From ICSID, Nafta, Bilateral Treaties and Customary International Law 341 (2005); see also Dolzer & Schreuer, supra note 11, at 34.

195 See, e.g., Statement by the Swiss Foreign Office, 1980 Annuaire Suisse de Droit International 178 (setting out the Swiss government’s position on the relationship between fair and equitable treatment and the minimum standard of treatment under customary international law), cited in Newcombe & Paradell, supra note 11, at 268, §6.21 n.173.

196 See supra text at notes 101-02.

197 See, e.g., Sempra Energy Int’l, supra note 67, Award, paras. 385-86 (Sept. 28, 2007); Enron, supra note 179, Award, para. 337 (May 22, 2007).

198 Dispute Regarding Navigational and Related Rights, supra note 109, para. 64.

199 Douglas, Hybrid Foundations, supra note 19, at 159.

200 Consider a bilateral investment treaty based on the U.S. model BIT. If the United States were the home state, the respondent state could cite provisions of the U.S. model BIT with which it agrees, while the claimant could cite provisions evidencing disagreement between the treaty parties. If the United States were the host state, then it could cite its model BIT to demonstrate that its arguments are supported by its general interpretive approach, while the claimant could use these terms to show any opportunistic arguments being made in the case.

201 A state may modify its model BIT to clarify its understanding of the original provision or to depart from a previous understanding. The same holds true for modifications between model BIT language and the actual investment treaty adopted. No hard-and-fast rule can be applied; the issue must be interpreted in the particular context. How a state characterizes its change provides useful evidence of its intention but cannot be determinative, or else it paves the way for disingenuous characterizations.

202 For example, the 2004 U.S. Model BIT, supra note 137, incorporates some tests from tribunal awards with which it agrees (such as in the definition of investment) and modifies other provisions so as to reject approaches taken by certain tribunal awards (such as in revisions to the provisions on expropriation and the minimum standard of treatment following various NAFTA cases). See generally Alvarez, supra note 65; Gagné & Morin, supra note 84; Vandevelde, supra note 84; Schwebel, supra note 84. For recent discussions of whether and how to review the 2004 U.S. Model BIT, see Report of the Advisory Committee, supra note 83.

203 See, e.g., Pan Am. Energy LLC v. Argentina, ICSIDNo. ARB/03/13, Preliminary Objections, para. 108 (July 27, 2006), available at http://ita.law.uvic.ca/; CMS Gas Transmission Co. v. Argentina, ICSID No. ARB/01/08, para. 368 (May 12, 2005), 44 ILM 1205 (2005) [hereinafter CMS Gas Award]; Enron Jurisdiction, supra note 179, para. 46; El Paso Energy Int’l Co. v. Argentina, ICSID No. ARB/03/15, Jurisdiction, para. 80 (Apr. 27, 2006), 21 ICSID Rev. 541 (2006).

204 A recent study of ICSID awards found only one instance in which a tribunal considered an argument based on a model BIT other than that of the United States, and in that case the tribunal rejected the argument. See Fauchald, supra note 1, at 348 n.250, citing Siemens, supra note 167, para. 106 (considering but rejecting an argument concerning the German model BIT in interpreting the Argentina-Germany BIT).

205 McLachlan, supra note 53, at 372.

206 See supra text at notes 120-21.

207 See, e.g., Bayview Irrigation Dist. No. 11 v. Mexico, ICSID No. ARB(AF)/05/1, para. 106 (NAFTA Ch. 11 Arb. Trib. June 19, 2007) (finding that an interpretation was supported by internal practice of each of the NAFTA parties, including the U.S. Statement of Administrative Action submitted to Congress in connection with NAFTA, the report on NAFTA prepared prior to the approval of that treaty by the Mexican Senate, and the Canadian Statement on Implementation of NAFTA). Numerous awards have referred to internal practice setting out one treaty party’s understanding of certain provisions at the point of ratification, such as explanations given by the U.S. executive when seeking ratification by the U.S. Senate. See, e.g., CMS Gas Award, supra note 203, paras. 362, 369; Generation Ukraine Inc. v. Ukraine, ICSID No. ARB/00/9, paras. 15.4-15.7 (Sept. 16, 2003), 44 ILM 404 (2005); CMS Gas Transmission Co. v. Argentina, supra note 203, Jurisdiction, para. 82 (July 17, 2003), 42 ILM 788 (2003); Feldmanv. Mexico, ICSID No. ARB(AF)/99/l, para. 181 (NAFTA Ch. 11 Arb. Trib. Dec. 16, 2002), 42 ILM 625 (2003); Mondev, supra note 170, para. 111. Some tribunals have referred to domestic judicial decisions of treaty parties as relevant practice. See, e.g., Enron Ancillary Claim, supra note 179, paras. 38-39 (referring to a decision of the U.S. Supreme Court on direct and indirect ownership that it found inconsistent with the position taken by Argentina in that case and by the United States in other cases, which demonstrated a lack of agreement on interpretation. See Dole Food Co., supra note 185).

208 Vienna Convention, supra note 2, Art. 27.

209 ADF Group, supra note 8.

210 Id., para. 188. The tribunal also noted that “domestic content and performance requirements in governmental procurement are by no means limited to the NAFTA Parties. To the contrary, they are to be found in the internal legal systems or in the administrative practice of many States.” Id.

211 See supra note 21.

212 See, e.g., Metalclad Corp. v. Mexico, ICSID No. ARB(AF)/97/l, para. 76 (NAFTA Ch. 11 Arb. Trib. Aug. 30, 2000), 40 ILM 36 (2001) (introducing a requirement for transparency and defining it as “the idea that all relevant legal requirements for the purpose of initiating, completing and successfully operating investments made, or intended to be made, under the Agreement should be capable of being readily known to all affected investors of another Party. There should be no room for doubt or uncertainty on such matters. Once the authorities of the central government of any Party. . . become aware of any scope for misunderstanding or confusion in this connection, it is their duty to ensure that the correct position is promptly determined and clearly stated so that investors can proceed with all appropriate expedition in the confident belief that they are acting in accordance with all relevant laws.”); Teemed Award, supra note 165, para. 154 (finding that fair and equitable treatment, “in light of the good faith principle established by international law, requires the Contracting Parties to provide to international investments treatment that does not affect the basic expectations that were taken into account by the foreign investor to make the investment. The foreign investor expects the host State to act in a consistent manner, free from ambiguity and totally transparently in its relations with the foreign investor, so that it may know beforehand any and all rules and regulations that will govern its investments, as well as the goals of the relevant policies and administrative practices or directives, to be able to plan its investment and comply with such regulations.”).

213 See Zachary, Douglas Nothing if Not Critical for Investment Treaty Arbitration: Occidental, Eureko a and Methanex, 22 ARB. Int’l 27, 28 Google Scholar (“The Teemed ’standard’ is actually not a standard at all; it is rather a description of perfect public regulation in a perfect world, to which all states should aspire but very few (if any) will ever attain.”); Saluka Partial Award, supra note 143, para. 304 (criticizing some formulations of the fair and equitable test as imposing “inappropriate and unrealistic” obligations if “taken too literally”).

214 See Van Harten, supra note 11, at 143-49; Kingsbury & Schill, supra note 21, at 6.

215 See supra text at notes 80-84.

216 See supra text at note 79.

217 See supra text at notes 77-78.

218 Sempra Jurisdiction, supra note 185, para. 147.