On 21^st May 2026 the International Court of Justice (ICJ) issued an advisory opinion of historic significance. The Governing Body of the International Labour Organization (ILO) requested an advisory opinion from the ICJ on the following question: “Is the right to strike of workers and their organizations protected under the Freedom of Association and Protection of the Right to Organise Convention, 1948 (No.87)?” The ICJ answered in the affirmative. On a correct legal interpretation of Convention No. 87, the right to strike is protected as an element of general freedom of association and the right to organise.

ILO Convention 87 is a fundamental ILO convention. The difficulty is that it does not contain an explicit textual reference to the right to strike. It is certainly not unique in this respect. The same is also true of Article 11 ECHR, which only explicitly protects “the right to form and join trade unions for the protection of his interests”. While the various ILO committees had converged on the proposition that the right to strike was impliedly encompassed by the general associative freedom protected in C.87, this consensus had been disrupted by the objections of the Employer’s Group within the tripartite ILO. This was also linked to constitutional objections to the Committee of Experts on the Application of Conventions and Recommendations to provide binding and authoritative interpretations of conventions. It developed into a full-blown constitutional crisis in 2012.

The derivation of the right to strike from the abstract guarantees in C.87 rested upon the interrelationship between three of its articles. Article 2 protects the right of “workers and employers” to “establish and…to join organisations of their own choosing”. Article 3 provides for the right of “organisations” to “draw up their constitutions and rules, to elect their representatives in full freedom, to organise their administration and activities and to formulate their programmes.” Finally, Article 10 defines a relevant organisation as “any organisation of workers or of employers for furthering and defending the interests of workers or of employers.” A good faith teleological interpretation of these provisions supported a right to strike. The strike is a means of action by which organisations further and defend the interests of workers.

From a labour law perspective, what does this opinion reveal about the parameters of the “right to strike” in international labour law?

What is a strike?

The generality of C.87, with its reference to “activities” without apparent delimitation, indicates a broad scope for a “strike”. The ICJ defines it as “an activity consisting of a temporary work stoppage or slowdown wilfully effected by one or more groups of workers with a view to enforcing or resisting demands or expressing or supporting grievances” ([70]). It is conceptualised as a form of trade union activity. There are two aspects of this definition that warrant emphasis. The first is its extension to a “slowdown”. This is wider than a “work stoppage”. It envisages the protection of forms of industrial action short of a full cessation of labour. The second is in its encompassing of “enforcing” or “resisting” demands. This must include strike action that is defensive (protecting existing terms) and strike action that is focused on improving terms and conditions. Elsewhere in the opinion, the ICJ also refers to collective action “to further and defend” the interests of members ([73]).

What lies at the core of the trade union activity of striking?

All rights have a core and a non-core or accessory range of application. For example, freedom of expression protects political speech at its core and pornography at its margins. The core of the right to strike, based in freedom of association, is as “a means of improving labour conditions and achieving sustained progress.” ([72]). This places “labour conditions” at the core of the right to strike. This does not mean that it is linked narrowly to the right to collective bargaining. The derivation from general freedom of association is broader than that. This is reflected in the interpretive primacy of C.87 rather than the other core freedom of association convention, C.98, which is focused on the right to collective bargaining. It is nevertheless implicit in this broader approach that primary strikes focused on occupational matters are at the core of the right to strike. This protection would also extend to some forms of socio-political and secondary action insofar as these activities protect and promote “labour conditions”.

What about the Committee of Experts?

The ICJ opinion also supports the weight and importance of ILO Committee pronouncements. While these committee decisions were not treated as binding on the ICJ, as expert bodies with specialist knowledge under the ILO constitutional structure, their decisions were to be ascribed “great weight” (118). There has been no indication that other courts such as the European Court of Human Rights (ECtHR) have had their confidence shaken in the ILO committees in right to strike cases following the 2012 Employer Group dispute. This observation cements the persuasive force of ILO committee decisions in other fora.

What about the content, scope or conditions for the right to strike?

The ICJ concluded that its opinion did not “entail any determination on the precise content, scope or conditions for the exercise of that right”. (140). Elsewhere in the opinion, in its discussion of the travaux to C.87, there was some discussion of the historical debates on the exclusion of the right to strike for certain occupational groups such as public servants. (104-111). While an advisory opinion was hardly the moment for an elaboration of the specific detail of the right to strike, this must be informed by the generality of the right to strike’s means and objects as determined by the opinion. And any interference with the right to strike must be proportionate and justified by legitimate aims.

The future of the right to strike in the international legal order

The significance of this opinion is better understood by reflecting on the counterfactual scenario. If the ICJ had found that the right to strike was not protected, this could have destabilised the entire international acquis on the right to strike (including the internal tripartite operation of the ILO itself). In jurisdictions such as the ECHR, the ILO material has been a keystone for the ECtHR’s “integrated” interpretative approach under Article 11. The ICJ advisory opinion prevents the risk of unravelling. In this respect, its impact is profound but only because of the door that was not opened. The profundity lies in what might have happened but did not.

It is less clear that the advisory opinion will lead to a radical reappraisal of judgments in the ECtHR that have been criticised as restrictive, such as RMT v UK [2014] ECHR 366 (UK ban on secondary action) and Humpert and others v Germany (ban on striking for civil servants). The generality of the protection for the trade union activity of striking leaves wide democratic space for content, scope and conditions.

The great irony of the ICJ advisory opinion is that the historic recognition of the right to strike was prompted by the Employer Group’s own “strike” within the ILO in 2012. This is a timely reminder that strategic actions can play out in all manner of unexpected ways.