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‘International Law is Part of the Law of the Land’: True or False?



This article addresses the question stated in its title by considering not only the role of national courts but also the roles of national legislatures and executives. That emphasis is called for because most of international law most of the time operates through national, rather than international, institutions and in particular through the executive and the legislature. Before I get to those national institutions, I consider two undisputed propositions of law, the varying characteristics of rules of international law and the impact of those characteristics on different national constitutional and legal systems.



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1 Alabama Claims Arbitration 1872 (United States of America v. United Kingdom), 1 J. B. Moore, International Arbitration 496 (1898).

2 Applicability of the Obligation to Arbitrate under Section 21 of the United Nations Headquarters Agreement of 26 June 1947, Advisory Opinion, [1988] ICJ Rep. 12 at 34, para. 57.

3 United Nations Conference on the Law of Treaties, First Session, Official Records, 72nd meeting, at 427–8. See now more generally Art. 3 of the ILC's Articles on the Responsibility of States for Internationally Wrongful Acts (2001).

4 Arts. 3, 47 and 57 of the United Nations Convention on the Law of the Sea 1982 (UNCLOS), 1833 UNTS 3.

5 See Art. 2 of the ILC Draft Articles on Diplomatic Protection and also Art. 19 and their commentaries (2006).

6 See McNair, A. D., ‘The Functions and Differing Legal Character of Treaties’, (1930) 11 BYIL 100.

7 At the normative level, see the General Assembly's Declaration on Principles of International Law Concerning Friendly Relations, GA Res.2625 (XXV). On the bilateral level, see the many treaties of ‘Friendship, Commerce and Navigation’, including those at issue in Military and Paramilitary Activities in and against Nicaragua (Nicaragua v. United States of America), Merits, Judgment, [1986] ICJ Rep. 14; and Oil Platforms (Islamic Republic of Iran v. United States of America), Judgment, [2003] ICJ Rep. 161.

8 As was recently affirmed by the ICJ, see Application of the International Convention on the Elimination of All Forms of Racial Discrimination (Georgia v. Russian Federation), Preliminary Objections, Judgment of 1 April 2011, at para. 37.

9 Courts in some jurisdictions invoke such international rules when interpreting domestic statutes and constitutional provisions (Sloss, D., ‘Treaty Enforcement in Domestic Courts: A Comparative Analysis’, in Sloss, D. (ed.), The Role of Domestic Courts in Treaty Enforcement: A Comparative Study (2009), 1 at 27–30; see also, in the same volume, J. Dugard, ‘South Africa’, 448, at 458, 469–70; J. Jayawickrama, ‘India’, 243 at 259–60; A. Nollkaemper, ‘The Netherlands’, 326 at 348–51).

10 Malachtou v. Armefti and Armefti (1987), 88 ILR 199, at 212.

11 See, for example, the procedural obligations imposed in the 1975 Statute of the River Uruguay, 1295 UNTS 339, Arts. 7–23, addressed by the ICJ in Pulp Mills on the River Uruguay (Argentina v. Uruguay), [2010] ICJ Rep. 14, 49–51, paras. 80–81.

12 For examples of problems which can arise where the implementing legislation departs from the text of the treaty, see In re H (Abduction: Custody Rights) [1991] 2 AC 476, where a UK statute had omitted certain provisions of the Hague Convention on International Child Abduction, and Gross v. Boda [1995] 1 NZLR 569, where the implementing statute used different terms from those used in the convention.

13 Bell, D., The Coming of Post-Industrial Society (1999), xviii, n. 6.

14 See discussion of varying attitudes in Australia and the UK in Crawford, J. R., ‘International Law in the House of Lords and the High Court of Australia 1996–2008: A Comparison’, (2009) 28 Australian Yearbook of International Law, 1; see also Sloss, supra note 9, at 6–8; on the evolving approach of English courts, see Higgins, R., ‘Dualism in the Face of a Changing Legal Culture’, in Schlemmer-Schulte, S. and Tung, Ko-Yung (eds.) Judicial Review in International Perspective: Liber Amicorum in Honour of Lord Slynn of Hadley, Vol. 2 (2000), 922; on the movement by American courts (in the opposite direction), see Bettauer, R. J., ‘Recent Books on International Law: Book Reviews’, (2011) 105 AJIL 397, at 401–3.

15 Waldron, J., ‘2009 Oliver Wendell Holmes Lectures: Dignity and Defamation: The Visibility of Hate’ (2010), 123 Harvard Law Review 1596.

16 Under Art. 4(2) of the Convention against Torture, for example, contracting states are obliged to make the relevant conduct ‘punishable by appropriate penalties which take into account their grave nature’ (1984 Convention against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment, 1465 UNTS 85). Similarly, Art. 5 of the Genocide Convention speaks of ‘effective penalties’ for persons guilty of the conduct described in that instrument.

17 Some useful sources on the former include: two reports by the New Zealand Law Commission (A New Zealand Guide to International Law and its Sources (1996 NZLCR 34) and The Treaty Making Process (1997 NZLC R45)); the ‘accession kits’ prepared by the Commonwealth Secretariat in respect of various international instruments, including model legislation and explanatory materials (earlier these focused on the Hague Conventions on private international law; a more recent example relating to the international counterterrorism conventions can be accessed at–88A5–46F2–8037-357DFF7D3EC1%7D_Implementation%20Kits%20for%20Counter-Terrorism.pdf); the database maintained by the International Committee of the Red Cross on domestic legislation giving effect to international humanitarian law (accessible at!OpenView); also Hollis, D., Blakeslee, M., and Ederington, B. (eds.), National Treaty Law and Practice (2005), which analyses practice in 19 states.

18 Crawford, J., ‘The International Law Standard in the Statutes of Australia and the United Kingdom’, (1979) 73 AJIL 638.

19 In English law, this phrase has been traced back to the mid-eighteenth century. See a valuable, questioning discussion in O'Keefe, R., ‘The Doctrine of Incorporation Revisited’, (2008) 79 BYIL 7, at 12–17.

20 R v. Jones (Margaret) [2006] UKHL 16 at para. 11; see also discussion in O'Keefe, supra note 19, at 55–63.

21 Crawford, supra note 14, at 6–7.

22 Contrast the approach taken by the Court of Appeal in Thai-Europe Tapioca Service Ltd v. Government of Pakistan, Ministry of Food and Agriculture, Directorate of Agricultural Supplies (Import and Shipping Wing) (The Harmattan) [1975] 1 WLR 1485, with the approach by the same Court (differently constituted) in Trendtex Trading Corporation v. Central Bank of Nigeria [1977] QB 529. In the latter, the Court found that that ‘the rules of international law, as existing from time to time, do form part of our English law. It follows . . . that a decision of this court – as to what was the ruling of international law 50 or 60 years ago – is not binding today’ (ibid., at 554).

23 The approach taken in Trendtex was subsequently approved by the House of Lords in 1 Congreso del Partido [1983] I AC 244. See also R v. Metropolitan Stipendiary Magistrate, ex parte Pinochet Ugarte (No. 1) [2000] 1 AC 61, 77; discussion in O'Keefe, supra note 19, at 78–84.

24 See, for example, the Criminal Code of Canada (R.S.C 1985, C-46), Art. 9(a); in the UK, see Knuller (Publishing, Printing and Promotions) Ltd v. Director of Public Prosecutions [1973] AC 435; more recently, in respect of international crimes, see R v. Jones (Margaret) [2006] UKHL 16, at paras. 23–29, 60–62, 101; R (Gentle) v. Prime Minister [2008] UKHL 20, at para. 49.

25 Oxford Reports on International Law in Domestic Courts (ILDC), accessible at

26 United States v. Smith (1820) 18 U.S. 5 Wheat 153; ILDC 1053 (U.S. 1820).

27 Fong Yue Ting and others v. United States (1893) 149 U.S. 698; ILDC 1051 (U.S. 1893).

28 The Paquete Habana and The Lola (1900) 175 U.S. 677; ILDC 392 (U.S. 1900).

29 Art. VI(2) of the Constitution of the United States provides in relevant part that ‘all Treaties made, or which shall be made, under the Authority of the United States, shall be the supreme Law of the Land; and the Judges in every State shall be bound thereby, any Thing in the Constitution or Laws of any State to the Contrary notwithstanding’.

30 In 1937, the Judicial Council of the Privy Council, on Appeal from the Supreme Court of Canada, stated that ‘Within the British Empire there is a well-established rule that the making of a treaty is an executive act, while the performance of its obligations, if they entail alteration of the existing domestic law, require legislative action.’ (Attorney-General for Canada v. Attorney-General for Ontario [1937] 8 ILR 41, 43; [1937] AC 326, 347).

31 See discussion in Sloss, supra note 9, at 38.

32 Medellin v. Texas, 136 ILR 689; 552 U.S. 491 (2008).

33 In the United States, see Roper v. Simmons (2005) 543 U.S. 551; in South Africa, see S v. Makwanyane and Another, (1995) 127 ILR 3.

34 Hosking v. Runting & Others [2004] NZCA 34; [2003] 3NZLR 385.

35 Lange v. Atkinson [2000] NZCA 95; [2000] 1 NZLR 257.

36 Ngati Apa, Ngati Koata and Others v. Attorney-General and Others [2003] NZCA 117.

37 R v. Decha-Iamsakun [1993] 1 NZLR 141.

38 See the statement by Lord Diplock in Salomon v. Commissioners of Customs and Excise [1967] 2 QB 116, at 143–4, discussed more recently by Lord Bingham in Al-Skeini and Others v. Secretary of State for Defence [2007] UKHL 26, at para. 12.

39 Sellers v. Maritime Safety Inspector [1999] 2 NZLR 44; nor is this a new approach, see R v. Keyn (1876) 2 Ex. D. 63, 85, and discussion in P. B. Maxwell, On the Interpretation of Statutes (1875), 123–4.

40 See, for example, the approach in Attorney-General v. Zaoui and Others [2005] NZSC 38.

41 For general discussion, see K. J. Keith, ‘Interpreting Treaties, Statutes and Contracts’, Occasional Paper No. 19, (2009) New Zealand Centre for Public Law.

42 See Huber, M., ‘Commentaire de l'interprétation des traités’, (1952) 44 (1)Annuaire de l'Institut de droit international, 198, at 200; discussed in Keith, supra note 41, at 54–6.

43 On the work of the International Law Commission on treaty interpretation, see Keith, supra note 41, at 21–8.

44 R v. Dodd (1874) 2 NZCA 598.

45 Dodd's counsel was Robert Stout (1844–1930), future Attorney-General (1878–79), Prime Minister (1884, 1884–87) and Chief Justice of New Zealand (1899–1926).

46 Lesa v. Attorney-General [1982] 1 NZLR 165; [1982] 79 ILR 684.

47 R (European Roma Rights Centre and Others) v. Immigration Officer at Prague Airport and Another (United Nations High Commissioner for Refugees Intervening) [2004] UKHL 55.

48 J. Kent, Commentaries on American Law, (1832), Vol. I, ‘Of the Law of Nations’, comprises Part I (at 1–200), while ‘Of the Government and Constitutional Jurisprudence of the United States’ follows in Part II (at 201–445)

49 Supra notes 1, 3.

* Judge of the International Court of Justice (2006–); Judge of the New Zealand Court of Appeal and Supreme Court (1996–2006), Member of the New Zealand Law Commission (1986–96) and Member of the Law Faculty, Victoria University, Wellington (1962–64, 1966–91). Thanks to Filippo Fontanelli and David McKeever for research assistance and comment. This paper is based on the keynote address given at the University of Glasgow, 19 May 2011, at a conference on International Law in Domestic Courts.



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