¹ Although foreign law is cited in many types of cases, the debate over legitimacy is fiercest in respect of constitutional cases. I suspect this is for a combination of two reasons: first, in constitutional cases, judicial power is at its greatest relative to other organs of government; second, constitutional cases often involve broad commitments giving greater interpretative freedom to judges. There is no common conception of ‘constitution’ across jurisdictions, but these two reasons point to the sorts of cases that are the subject of this debate.

² Scalia, A, ‘Commentary’ (1996) 40 St Louis University Law Journal 1119, 1121Google Scholar.

³ Bingham, T, Widening Horizons (Cambridge University Press, Cambridge, 2009)Google Scholar 6. Bingham’s comments are not limited to the constitutional context. This article does not address the citation of foreign law in other contexts, in respect of which different considerations may arise.

⁴ See Glenn, HP, ‘Persuasive Authority’ (1987) 32 McGill Law Journal 261;Google Scholar Schauer, F, ‘Authority and Authorities’ (2008) 94 Virginia Law Review 1931Google Scholar; and Waldron, J, Partly Laws Common to All Mankind (Yale University Press, New Haven, CT, 2012).Google Scholar

⁵ See Markesinis, B with Fedtke, J, Engaging with Foreign Law (Hart Publishing, Oxford, 2009);Google Scholar Slaughter, A, A New World Order (Princeton University Press, Princeton, NJ, 2004);Google Scholar and the comments of Breyer in A Scalia and Breyer, S, ‘A Conversation between US Supreme Court Justices’ (2005) 3 International Journal of Constitutional Law 519Google Scholar.

⁶ Claire L’Heureux-Dubé presents judicial dialogue as an enhanced form of judicial learning; C L’Heureux-Dubé, The Importance of Dialogue: Globalization and the International Impact of the Rehnquist Court (1998) 34 Tulsa Law Journal 15, 17. Sujit Choudhry presents judicial dialogue as something akin to a dialectical comparison of national law with foreign law; Choudhry, S, ‘Globalisation in Search of Justification: Toward a Theory of Comparative Constitutional Interpretation’ (1999) 74 Indiana Law Journal 819, 858Google Scholar. Markesenis and Fedtke raise the possibility of an interjurisdictional discussion among judges, carried on through their written judgments, about the meaning of rights and other constitutional issues; see (n 5) 48.

⁷ This assumes that it is not democratic for, say, the people of Switzerland to make laws for the people of Austria, even if the law-making procedures employed would be unimpeachably democratic if the Swiss were making laws for themselves.

⁸ In a survey of apex court judges, Flanagan and Ahern uncover some evidence that judges engage in such references. Flanagan, B and Ahern, S, ‘Judicial Decision-Making and Transnational Law: A Survey of Common Law Supreme Court Judges’ (2011) 60 International and Comparative Law Quarterly 1, 23CrossRefGoogle Scholar.

⁹ For instance, there may be differences between common law and civil law jurisdictions. For an example of this approach, see Saunders, C, ‘Judicial Engagement with Comparative Law’ in Ginsberg, T and Dixon, R (eds), Comparative Constitutional Law (Edward Elgar, Cheltenham, 2011).Google Scholar

¹⁰ Scalia (n 2) 1122.

¹¹ Perju, V, ‘Constitutional Transplants, Borrowing, and Migrations’ in Rosenfeld, M and Sajó, A (eds), Oxford Handbook of Comparative Constitutional Law (Oxford University Press, Oxford, 2012).Google Scholar

¹² For strains of this approach, see Tushnet, M, ‘Transnational/Domestic Constitutional Law’ (2004) 37 Loyola of Los Angeles Law Review 239, 264Google Scholar and Jackson, VC, ‘Constitutional Comparisons: Convergence, Resistance, Engagement’ (2005) 119 Harvard Law Review 109, 119Google Scholar.

¹³ Waldron (n 4) 21.

¹⁴ Ibid 61.

¹⁵ Sedley, S, ‘Constitutional Court Judges Roundtable’ (2005) 3 International Journal of Constitutional Law 569, 570CrossRefGoogle Scholar.

¹⁶ Glenn (n 4) 263.

¹⁷ Schauer (n 4).

¹⁸ Ibid 1946.

¹⁹ Raz has been the leading exponent of attempts to understand law in terms of authority. See, for instance, Raz, J, The Authority of Law (Clarendon Press, Oxford, 1979).Google Scholar The purpose here, however, is not to defend the use of authority in a general understanding of law but rather to introduce a series of distinctions around authority that helps inform the foreign law debate. For my own views on Raz’s concept of authority, which inform the shorter account given here, see Doyle, O, ‘The Legitimate Authority of the Living Law’ (2012) 3 Jurisprudence 113Google Scholar.

²⁰ This avoids a further problem in explaining law in terms of authority – the question of whether law can claim at all. On that problem, see Dworkin, R, ‘Thirty Years On’ (2002) 115 Harvard Law Review 1655CrossRefGoogle Scholar and Gardner, J, Law as a Leap of Faith (Oxford University Press, Oxford, 2012) 125.CrossRefGoogle Scholar

²¹ Tushnet, ‘Transnational/Domestic Constitutional Law’ (n 12) and Jackson, ‘Constitutional Comparisons: Convergence, Resistance, Engagement’ (n 12).

²² Flanders, C, ‘Toward a Theory of Persuasive Authority’ (2007) 62 Oklahoma Law Review 55Google Scholar. Flanders is discussing persuasive authority as between different States. Obviously, the citation of foreign case law is considerably more problematic in the USA. Similarly, Jackson considers that the fact that the foreign case law speaks as law in another jurisdiction puts it in a different category from scholarly articles. Jackson, VC, Constitutional Engagement in a Transnational Era (Oxford University Press, Oxford, 2010) 148.Google Scholar

²³ Ackermann, LWH, ‘Constitutional Comparativism in South Africa: A Response to Sir Basil Markesinis and Jörg Fedtke’ (2005) 80 Tulane Law Review 169, 183Google Scholar. For the same view, see Barak, A, ‘Response to The Judge as Comparatist: Comparison in Public Law’ (2005) 80 Tulane Law Review 196, 198Google Scholar.

²⁴ Markesenis with Fedtke, Engaging with Foreign Law (n 5) 132.

²⁵ Slaughter, A New World Order (n 5) 69.

²⁶ Jackson, VC, ‘Narratives of Federalism: Of Continuities and Comparative Constitutional Experience’ (2001) 51 Duke Law Journal 223, 254CrossRefGoogle Scholar.

²⁷ Jackson, ‘Constitutional Comparisons: Convergence, Resistance, Engagement’ (n 12) 110. Choudhry makes a similar point: S Choudhry, ‘Globalization in Search of Justification: Toward a Theory of Comparative Constitutional Interpretation’ (n 6) 858.

²⁸ Breyer (n 5) 524.

²⁹ Markesenis with Fedtke, Engaging with Foreign Law (n 5) 161.

³⁰ 543 US 551 (2005). The issue was whether the 8th Amendment to the US Constitution prohibits the imposition of the death penalty for offences committed by minors.

³¹ Hoffmann-Riem, W, ‘Constitutional Court Judges’ Roundtable’ (2005) 3 International Journal of Constitutional Law 556, 559CrossRefGoogle Scholar.

³² Bader Ginsburg, R, ‘A Decent Respect to the Opinions of [Human]kind: The Value of a Comparative Perspective in Constitutional Adjudication’ (2005) 64 Cambridge Law Journal 575, 580CrossRefGoogle Scholar.

³³ [1995] ZACC 3.

³⁴ Ibid [34]. Section 35(1) of the Interim Constitution required the Constitutional Court, when considering human rights claims under the Constitution, to have regard to applicable provisions of international law and permitted the Court ‘to have regard to comparable foreign case law’. This provision, broadly replicated in section 39(1) of the current Constitution, is relevant to the legitimacy of having regard to foreign law but does not necessarily affect the way in which foreign law is used.

³⁵ Ibid [56].

³⁶ Ibid [37].

³⁷ Perju (n 11) 1318.

³⁸ L’Heureux-Dubé, ‘The Importance of Dialogue: Globalization and the International Impact of the Rehnquist Court’ (n 6) 15, 17. See also McCrudden, C, ‘A Common Law of Human Rights?: Transnational Judicial Conversations on Human Rights’ (2000) 20 OJLS Oxford Journal of Legal Studies 499, 528CrossRefGoogle Scholar; Slaughter, A, ‘A Global Community of Courts’ (2003) 44 Harvard International Law Journal 191, 193Google Scholar; Markesinis with Fedtke, Engaging with Foreign Law (n 5) 17, 47; Bryde, B-O, ‘The Constitutional Judge and the International Constitutionalist Dialogue’ (2005) 80 Tulane Law Review 203Google Scholar; Canivet, G, ‘The Practice of Comparative Law by the Supreme Courts: Brief Reflections on the Dialogue between the Judges in French and European Experience’ (2005) 80 Tulane Law Review 1377Google Scholar; Perju, V, ‘The Puzzling Parameters of the Foreign Law Debate’ (2007) 20 Utah Law Review 167, 182Google Scholar; V Perju, ‘Constitutional Transplants, Borrowings and Migrations’ (n 11) 1324; Choudhry, S, ‘Migration as a New Metaphor in Comparative Constitutional Law’ in Choudhry, S (ed), The Migration of Constitutional Ideas (Cambridge University Press, Cambridge, 2006)Google Scholar 22; G Halami, ‘The Use of Foreign Law in Constitutional Interpretation’ in Rosenfeld and Sajó (n 11) 1328.

³⁹ Flanagan and Ahern (n 8) 16.

⁴⁰ Jackson notes that dialogue implies a conversation that may not always be taking place. For this reason, she prefers the broader term ‘engagement’. Jackson, Constitutional Engagement in a Transnational Era (n 22) 71. ‘Engagement’ encompasses and perhaps is co-extensive with the notion of judicial learning under consideration here. L’Heureux-Dubé distinguishes dialogue from one-way transmission, again suggesting that what she has in mind is reciprocal listening more than dialogue in the sense of two courts speaking to each other. L’Heureux-Dubé, ‘The Importance of Dialogue: Globalization, the Rehnquist Court, and Human Rights’ (n 6) 236.

⁴¹ Choudhry, ‘Globalization in Search of Justification: Toward a Theory of Comparative Constitutional Interpretation’ (n 6). Yap refers to this as the diagnostic value of foreign law. See Yap, P-J, ‘Transnational Constitutionalism in the United States: Toward a Worldwide Use of Interpretive Modes of Comparative Reasoning’ (2005) 39 University of San Francisco Law Review 999, 1001Google Scholar.

⁴² 543 US 551 (2005).

⁴³ Sedley (n 15) 570.

⁴⁴ The arguments from democracy presuppose that normative force within the national system is being granted to the foreign law. See Alford, RP, ‘In Search of a Theory for Constitutional Comparativism’ (2004) 52 University of California Los Angeles Law Review 639, 710–11Google Scholar and Levinson, S, ‘Looking Abroad When Interpreting the US Constitution: Some Reflections’ (2004) 39 Texas International Law Journal 353, 363–4Google Scholar. For a response, see Tushnet, ‘Transnational/Domestic Constitutional Law’ (n 12).

⁴⁵ Flanders has made similar points in addressing the slightly different question of why judges treat cases from outside their legal system as having more persuasive authority than other non-binding sources. Flanders (n 22) 71–2. Tushnet also endorses the notion that a judicial decision carries weight ‘akin to a warranty that the decision maker was fully serious in arriving at his or her normative conclusion’. Tushnet, M, ‘When is Knowing Less Better than Knowing More? Unpacking the Controversy over Supreme Court Reference to Non-US Law’ (2006) 90 Minnesota Law Review 1275, 1285–6Google Scholar.

⁴⁶ Jackson, Constitutional Engagement in a Transnational Era (n 22) 174–5.

⁴⁷ [2012] IESC 10. This is not a typical example of how the Irish Supreme Court treats foreign case law.

⁴⁸ 450 US 464 (1981).

⁴⁹ O’Sullivan, C, ‘Protecting Young People from Themselves: Reforming the Age of Consent Law in Ireland’ (2009) 31 Dublin University Law Journal 386Google Scholar.

⁵⁰ Ackermann (n 23) 181.

⁵¹ Barak (n 23) 196; Canivet (n 38) 1396; L’Heureux-Dubé (n 38) 23. Thirty-five of the 43 respondents to Flanagan and Ahern’s survey indicated that a democratic form of governance was a prerequisite for the citation of the law of another jurisdiction. Flanagan and Ahern (n 8) 21.

⁵² See Ramsay, M, ‘International Materials and Domestic Rights: Reflections on Atkins and Lawrence’ (2004) 98 American Journal of International Law 69, 74CrossRefGoogle Scholar.

⁵³ Markesenis with Fedtke, Engaging with Foreign Law (n 5) 48.

⁵⁴ Slaughter, ‘A Global Community of Courts’ (n 38) 198.

⁵⁵ SD O’Connor, ‘Remarks to the Southern Center for International Studies’ Atlanta, USA 28 October 2003. The official transcript of Justice O’Connor’s remarks is no longer hosted at <http://southerncenter.org/OConnor_transcript.pdf>. However, the text is available at <http://www.humanrightsfirst.org/wp-content/uploads/pdf/SOUTHERN_CENTER_INTERNATIONAL_STUDIES_Justice_O’Connor.pdf>.

⁵⁶ Breyer (n 5) 524. Slaughter explicitly links the incentive to pride in a cosmopolitan judicial outlook. Slaughter, A New World Order (n 5) 75. For criticism, see Waldron (n 4) 81; Choudhry, Migration (n 38) 7.

⁵⁷ This is the charge laid by Scalia J of the US Supreme Court against the majority judges in Roper v Simmons 543 US 551 (2005), namely that they do not have regard to foreign law where it is less liberal than the law in the US. See also Sullivan, B, ‘Constitutional Interpretation as Interfaith Communion: the Use of Foreign Legal Materials in US Courts’ (May 2007) Newsletter International Litigation News 44Google Scholar; Hirschl, R, ‘On the Blurred Methodological Matrix of Comparative Constitutional Law’ in Choudhry, Migration (n 38) 43Google Scholar.

⁵⁸ VC Jackson, ‘Comparative Constitutional Law: Methodologies’ in Rosenfeld and Sajó (n 11) 70. Posner comments that ‘foreign decisions emerge from complex social, political, cultural, and historical backgrounds of which Supreme Court Justices, like other American judges and lawyers, are largely ignorant’. R Posner, ‘Foreword: A Political Court’ (2005) 119 Harvard Law Review 31, 86.

⁵⁹ Markesinis with Fedtke, Engaging with Foreign Law (n 5) 114.

⁶⁰ Sullivan (n 57).

⁶¹ It is for this reason that any lack of expertise on the part of judges is not a consideration that militates against their consideration of national law. The justification for judges to have regard to national law is so strong that it outweighs any concern that a particular judge might not have the relevant expertise on a particular area of the law.

⁶² Jackson, ‘Narratives of Federalism’ (n 26). See also L’Heureux-Dubé, The Importance of Dialogue (n 6) 38.

⁶³ Kentridge, S, ‘Comparative Law in Constitutional Adjudication: The South African Experience’ (2005) 80 Tulane Law Review 245, 245Google Scholar.

⁶⁴ See O Doyle, ‘Conventional Constitutional Law’ (2015) 38 Dublin University Law Journal 311.

⁶⁵ See Zhou, H-R, ‘A Contextual Defense of “Comparative Constitutional Common Law”’ (2014) 12 International Journal of Constitutional Law 1034CrossRefGoogle Scholar.

⁶⁶ Kentridge (n 63) 245.

⁶⁷ 521 US 702 (1987).

⁶⁸ See for instance S Levinson (n 44).

⁶⁹ Jackson, ‘Constitutional Comparisons’ (n 12), citing Wilkerson v Utah 99 US 130, 134 (1879).

⁷⁰ 543 US 551 (2005).