Written by Ellasandra Hahn

Introduction

International law presents a notoriously tricky challenge: who makes, defines, and enforces the rules? The United Nations tried to address these questions through the International Court of Justice (“ICJ”).¹See U.N. Charter art. 7, ¶ 1, art. 36, ¶ 3, arts. 92–96. While it is the preeminent body designed to settle disputes between States and issue advisory opinions, the ICJ’s authority is precarious.²Id. art. 93, ¶ 1. States must consent to its jurisdiction, and more importantly, enforcement for a binding ICJ judgment is dependent on the unanimous vote of five permanent members (“P5”) of the UN Security Council (“UNSC”).³Id.; id. art. 94, ¶ 2. The ongoing ICJ case Iran v. Canada highlights this fragility.⁴See Alleged Violations of State Immunities (Iran v. Can.), Application Instituting Proceedings, 2023 I.C.J. 189, ¶ 2 (June 27) (contending that Canada violates Iran’s sovereign immunity protected by international law). The ICJ must balance a misalignment between accepted state practice under opinio juris and the interests of powerful States, whose veto power on the UNSC makes them and their allies essentially immune to legal accountability, irrespective of a binding judgment against them.⁵See Statute of the International Court of Justice, art. 38, ¶ 1(b), June 26, 1945, 59 Stat. 1055, U.N.T.S. 993 (declaring international custom a source of law); see U.N. Charter art. 94, ¶ 2 (delegating enforcement of ICJ rulings to the UNSC). For the few and the mighty, the rules of the game are heads I win, tails you lose.

Background

The ICJ’s jurisdiction is founded on the consent of States, which can be granted on a case-by-case basis or through a declaration of compulsory jurisdiction.⁶Statute of the International Court of Justice, art. 36, ¶ 2, June 26, 1945, 59 Stat. 1055, U.N.T.S. 993. However, major powers, including China, Russia, and the U.S., have withdrawn or never agreed to compulsory jurisdiction.⁷The World Court is in Session: Here’s What to Know, Better World Campaign Blog (May 1, 2025), https://betterworldcampaign.org/blog/understanding-international-court-of-justice. This voluntary nature of consent creates a loophole, allowing powerful States to selectively accept the Court’s authority.

Even with consent, a successful judgment faces an enforcement hurdle. A party must appeal to the UNSC to enforce the ruling, which has never successfully occurred.⁸U.N. Charter art. 94, ¶ 2; In Hindsight: The Security Council and the International Court of Justice, Sec. Council Rep. (Dec. 28, 2016), https://www.securitycouncilreport.org/monthly-forecast/2017-01/in_hindsight_the_security_council_and_the_international_court_of_justice.php. In the 1986 case Nicaragua v. U.S., the ICJ ruled that U.S. support for Nicaraguan rebels violated international law.⁹Military and Paramilitary Activities in and Against Nicaragua (Nicar. v. U.S.), Judgment, 1986 I.C.J. Rep. 14, ¶ 190 (June 27). A draft resolution to enforce the ICJ’s ruling against the U.S. was brought to the UNSC, but was vetoed by the U.S. (a party to the case).¹⁰See Congo, Ghana, Madag., Trin. & Tobago and U.A.E., draft resolution [on the International Court of Justice judgement of 27 June 1986], U.N. Doc. S/18428 (Oct. 28, 1986) (requesting that the UNSC enforce the ICJ judgment against the U.S.); see also U.N. SCOR, 41st Sess., 2718th mtg. at 51, U.N. Doc. S/PV.2718 (Oct. 28, 1986) (documenting the failure of the draft resolution due to the U.S.’ negative vote). This set the precedent for P5 members voting to protect their political interests and those of their allies, rendering enforcement of ICJ rulings little more than a utopian ideal.

The ICJ case that Iran brought against Canada in June 2023, Alleged Violations of State Immunities (Iran v. Canada), brings these issues to the fore.¹¹See generally Alleged Violations of State Immunities (Iran v. Can.), Application Instituting Proceedings, 2023 I.C.J. 189, ¶ 2 (June 27). Iran alleges that Canada violates international law with its Justice for Victims of Terrorism Act (“JVTA”).¹²Id.; Justice for Victims of Terrorism Act, S.C. 2012, c. 1, s. 2 (Can.) [hereinafter JVTA]. This law allows any victim of terrorism to sue States that Canada has designated as sponsors of terrorism in Canadian courts.¹³U.N. Charter art. 94, ¶ 2. Iran argues that this violates their sovereign immunity, which it considers to be a customary international law bound by opinio juris.¹⁴Iran v. Can. ¶ 21. Canada’s laws closely resemble the U.S.’ Foreign Sovereign Immunities Act (“FSIA”).¹⁵28 U.S.C. §§ 1602-1611. Canada and the U.S. are the only States with such exceptions.¹⁶Maryam Jamshidi, Iran’s ICJ Case Against Canada Tests the Terrorism Exception to Sovereign Immunity, Just Security (July 24, 2023), https://www.justsecurity.org/87357/irans-icj-case-against-canada-tests-the-terrorism-exception-to-sovereign-immunity/. The dispute highlights the conflict between the customary norm of State immunity and the emerging counter-norm of exceptions for terrorism.¹⁷G.A. Res. 59/38, Convention on Jurisdictional Immunities of States and Their Property, (Dec. 2, 2004).

Analysis

Customary international law is the second source of law in the ICJ Statute.¹⁸Statute of the International Court of Justice art. 38, ¶ 1(b), June 26, 1945, 59 Stat. 1055, 33 U.N.T.S. 993. It follows from (1) a consistent practice across States and (2) States’ subjective belief that the practice is legally binding, known as opinio juris.¹⁹Ronald Alcala, Opinio Juris and the Essential Role of States, Lieber Inst. West Point (Feb. 11, 2021), https://lieber.westpoint.edu/opinio-juris-essential-role-states/. The unratified UN Convention on Jurisdictional Immunities of States and Their Properties, adopted in 2004, aimed to codify the principles of state immunity.²⁰G.A. Res. 59/38, Convention on Jurisdictional Immunities of States and Their Property, (Dec. 2, 2004). Notably, the Convention does not mention a terrorism exception, highlighting a lack of international consensus on the issue.²¹Id.

The Iran v. Canada case provides a contemporary example of the ICJ’s systematic flaws in addressing emerging legal norms.²²See generally Alleged Violations of State Immunities (Iran v. Can.), Application Instituting Proceedings, 2023 I.C.J. 189, ¶ 2 (June 27). Iran claims that Canada’s JVTA violates customary international law on sovereign immunity, for which terrorism is no exception.²³Id. ¶ 2; JVTA, supra note 12. While there is evidence of an opinio juris from the majority of States supporting this position, including the U.N. Convention on State immunities, there is also evidence of a growing acceptance of a terrorism exception among powerful States.²⁴Compare G.A. Res. 59/38, Convention on Jurisdictional Immunities of States and Their Property, (Dec. 2, 2004), and Letter from Eur. Union Delegation to the U.S., to U.S. Dep’t of State (Sept. 9, 2016) (on file with the Washington Post) (expressing the European Union’s concerns about the U.S.’ legislation allowing individuals to sue states sponsoring terrorism, which it views as “in conflict with fundamental principles of international law and in particular the principle of State sovereign immunity”)., with S.C. Res. 1373, U.N. Doc. S/RES/1373 (Sept. 28, 2001) (expressing the UNSC’s support for national counterterrorism measures following the Sept. 11 attacks). The U.S. and Canada codified this counter-norm, and the UNSC indicated support for stronger legislative measures against terrorism.²⁵See S.C. Res. 1373, ¶ 1 U.N. Doc. S/RES/1373 (Sept. 28, 2001). This type of emerging counter-norm challenging the fixed ideal of a customary rule creates a source of law dilemma for the consent-based ICJ, particularly when influential States are on each side. ²⁶Statute of the International Court of Justice art. 38, ¶ 1(b); Alcala, supra note 19.

The greater tragedy of the case, however, is the political reality of enforcement. The structure of international law and its enforcement mechanisms ensure that the political interests of powerful nations trump the Court’s authority.²⁷U.N. Charter art. 94, ¶ 2. Even if the ICJ were to rule in favor of Iran and uphold the customary rule of sovereign immunity, the ruling would likely be unenforceable. The U.S. would almost certainly use its veto power as a P5 to block an enforcement resolution, given its similar legislation.²⁸Compare 28 U.S.C. § 1605A (determining a foreign state shall not be immune from suit in any case “in which money damages are sought against a foreign state for personal injury or death that was caused by an act of torture, extrajudicial killing, aircraft sabotage, hostage taking, or the provision of material support or resources for such an act.”), with JVTA supra note 12, art. 6.1(1) (determining “[a] foreign state [listed as a sponsor of terrorism] is not immune from the jurisdiction of a court in proceedings against it for its support of terrorism on or after January 1, 1985”). The U.S. did so in Nicaragua v. U.S., the only case where the UNSC was asked to enforce an ICJ ruling, demonstrating that P5 members are willing to protect their political interests over the ICJ’s verdict.²⁹U.N. SCOR, 41st Sess., 2718th mtg. at 51, U.N. Doc. S/PV.2718 (Oct. 28, 1986). Regardless of what the ICJ decides, the outcome of the case remains the same: Canada will not need to change its legislation.³⁰U.N. Charter art. 94, ¶ 2. For powerful States, the ICJ’s authority is conditional and non-binding.

Conclusion

The ICJ’s dual reliance on State consent for jurisdiction and on the UNSC for enforcement renders it effective only for States willing to comply or those whose allies lack veto power.³¹See id. The Iran v. Canada case provides a powerful example of this: the only inevitable outcome is that Canada can keep its terrorism exception.³²See generally Alleged Violations of State Immunities (Iran v. Can.), Application Instituting Proceedings, 2023 I.C.J. 189, ¶ 2 (June 27). Without a structural UNSC reform—specifically, the P5’s veto power—rulings against powerful States remain unenforceable.³³See U.N. Charter art. 94, ¶ 2.

One way to address this gap is to establish the ICJ’s own enforcement body, composed of consenting States–effectively, its own UNSC with the ability to deploy Peacekeepers, administer sanctions, and so forth. While the UNSC would likely not vote to give the ICJ enforcement authority, thereby undermining its own, this would address the issue of P5 political interests determining justice. Another approach is to exempt a resolution to enforce ICJ rulings from a UNSC veto altogether, reflecting the binding nature of the Court’s judgment.³⁴See id. While the P5 may debate the method of enforcement, the inability to disregard a resolution to enforce an ICJ ruling would provide significant validity to the ICJ. The Iran v. Canada case is a powerful example of the necessity and gaps in international law.³⁵See generally Iran v. Can. Just as the house always wins at blackjack, those who built the system are always able to walk away with the biggest winnings.