Environment — Transboundary pollution — Rivers — River constituting international boundary — River Uruguay — Regime for balancing economic development with protection of riverine environment — Boundary treaty between Argentina and Uruguay concluded in 1961 — Statute of the River Uruguay, 1975 — Procedural and substantive obligations — Proof of breach of substantive obligations — Evidence of effect of discharges upon water quality

Environment — General principles of international environmental law — Principle of prevention — Precautionary principle — Requirement to conduct environmental impact assessment — Scope and conduct of environmental impact assessment

International Court of Justice — Provisional measures of protection — Criteria — Requirement that measures must be urgently needed to protect rights which might form subject of judgment — Request for provisional measures by Respondent — Whether appropriate to order Applicant to prevent blockade of bridge by private citizens — Measures calling upon Parties to abstain from conduct likely to aggravate or extend dispute

International Court of Justice — Evidence — Burden of proof — Standard of proof — Scientific evidence — Power of Court to appoint expert — Power of Court to make own inquiry into facts — Expert evidence — Experts appearing as counsel — Whether evidence sufficient to establish harmful environmental effects — Appraisal of scientific evidence by Court

International organizations — Administrative Commission of the River Uruguay (CARU) — Legal personality — Nature and role of CARU — Whether more than a framework for discussions between States Parties — Regulatory role

Rivers — Pollution — River Uruguay — Regime for balancing economic development with protection of riverine environment — Boundary treaty between Argentina and Uruguay concluded in 1961 — Statute of the River Uruguay, 1975 — Protection of water quality and environment

Treaties — Interpretation and application — Treaty on environmental protection — Interlocking nature of obligations — Procedural and substantive obligations