Last week the International Court of Justice (ICJ) delivered, by ten votes to four, the advisory opinion that workers’ organizations have awaited for fourteen years. The right to strike of workers and their organizations is protected under the International Labor Organization’s (ILO) Freedom of Association and Protection of the Right to Organise Convention, 1948 (No. 87). The question put to the Court by the ILO Governing Body, the organization’s executive body, in November 2023 has been answered in the affirmative.

The ICJ reached its opinion interpreting Convention No. 87 under the customary rules reflected in Articles 31 and 32 of the Vienna Convention on the Law of Treaties (VCLT). Applying Article 31(1), which requires a treaty “be interpreted in good faith in accordance with the ordinary meaning to be given to the terms of the treaty in their context and in the light of its object and purpose”, the Court reads the ordinary meaning of “activities” and “programmes” in Article 3 in conjunction with Article 2 (the right to form and join organizations) and Article 10 (the purpose of such organizations, namely furthering and defending workers’ and employers’ interests). The Court observes that strike action is “capable of falling within the ordinary meaning of the term ‘activities'” and is not “explicitly excluded” by the Convention’s two express limitations. The object and purpose analysis is pointed – “strike action is one of the main activities engaged in and tools used by workers and their organizations to promote their interests and improve conditions of labour, thereby ensuring the effective exercise of the freedom of association is protected under Convention No. 87.”

The Court’s discussion of Article 31(3)(c) of the VCLT is particularly important. That article provides that when interpreting a treaty, international tribunals must take into account “any relevant rules of international law applicable in the relations between the parties”. The Court takes Article 8 of the International Covenant on Economic, Social and Cultural Rights (ICESCR) and Article 22 of the International Covenant on Civil and Political Rights (ICCPR) as “relevant rules of international law applicable in the relations between the parties,” noting the high degree of overlap between ratifications and the Human Rights Committee’s twenty-five years of practice treating the right to strike as encompassed within ICCPR Article 22. For litigants invoking the right to strike before regional and domestic fora, this cross-instrumental reading particularly helpful – especially in the small number of countries which have not ratified Convention 87.

Perhaps the most consequential paragraph for the ILO supervisory system, the term for the group of committees that assess the extent of member state compliance with ILO conventions, is paragraph 118. There, the Court extends its reasoning in Ahmadou Sadio Diallo. In that case, the Court accorded “great weight” to the observations of the Human Rights Committee. The Court holds that it may ascribe great weight to the pronouncements of ILO supervisory bodies as a supplementary means of interpretation. The Committee of Experts on the Application of Conventions and Recommendations (CEACR) and the Committee on Freedom of Association (CFA) are not, in its framing, expert treaty bodies of the conventional kind but they perform a functionally equivalent role. Importantly, the CEACR has since 1959 maintained that Article 3 of Convention No. 87 protects the right to strike. The CFA has done the same for nearly as long. The employers’ group has insisted since at least 2012 that the supervisory bodies exceeded their mandate. That position has now been comprehensively rejected by the principal judicial organ of the United Nations. This grant of deference to the ILO supervisory system affirms the interpretative competence of the CEACR which the employers have strenuously questioned. The CEACR’s reading of Convention No. 87, and the attendant observations on the scope of the right to strike, carries “great weight” before the International Court of Justice. That is a powerful endorsement, and one that is useful beyond this specific case.

The analysis of the preparatory materials is also notable for what the Court does not find. The core of the employers’ group’s argument was that the drafters of Convention 87 had affirmatively decided to exclude the right to strike from the scope of the convention. However, the Court concluded that the drafting history was at best “inconclusive”. In fact, the Court found that questions about the right to strike were largely confined to whether public officials had that right, not about the right in general. Further, the silence of the final text does not sustain the employers’ group’s argument.

From a practitioner’s perspective, a national legal regime that prohibits the strike, or that subjects it to disproportionate restriction, can now be challenged not only on the strength of the CEACR’s interpretation, but on the strength of the ICJ’s confirmation of it. Domestic courts asked to construe constitutional or statutory provisions on freedom of association in the light of Convention No. 87 now have an authoritative international determination to cite. Importantly, the regional human rights bodies, such as the African Commission, the Inter-American Court, the European Court of Human Rights, have had their existing jurisprudence on the right to strike vindicated, and may prove to be welcoming jurisdictions to developing not only the right to strike but other labor rights which are developed in dialogue with the ILO supervisory system. Further, the Court’s use of the ICESCR and the ICCPR as interpretative aids provides a template for arguing the meaning of other ILO instruments where the supervisory bodies have developed interpretations that some States resist.

The concurring declaration of US judge Sarah Cleveland takes the Court’s arguments to their logical conclusion, concluding that “given the breadth of recognition of the right to strike in numerous overlapping international and regional instruments, as well as in bilateral and trade agreements, the constitutional protection of the right to strike in at least 97 States and its legislative protection in more than 150 others, a compelling case can be made that protection of the right to strike is a principle of customary international law.”  

The 2012 crisis, when the employers at the ILO denied the existence of a right to strike under Convention 87, was, at root, a challenge to whether the supervisory system could be trusted to mean what it said. That challenge has been resolved in the supervisory system’s favor by the only body whose word on the question could carry final weight. Today’s opinion is the closing of a chapter, but the work continues. The Court’s conclusion “does not entail any determination on the precise content, scope or conditions for the exercise of [the right to strike].” The contest over the exact scope of the right and permissible limitations remains live. The CEACR and the CFA will resume that work, as they have been entrusted to do.

As worker rights are under attack worldwide, the legal and moral clarity of the opinion is a very welcome development.