ICJ Advisory Opinion on the Right to Strike: Implications for the UK

On 21 May 2026, the International Court of Justice (ICJ) delivered its advisory opinion in Right to Strike under ILO Convention No. 87, holding, by ten votes to four, that “the right to strike of workers and their organizations is protected” under the Freedom of Association and Protection of the Right to Organise Convention, 1948 (No. 87). The opinion resolves a long-running disagreement between the International Labour Organisation’s (ILO) core constituents – governments, employers and workers – following a referral to the ICJ in November 2023.

Although advisory and non-binding on the UK courts, the opinion carries authoritative weight as the definitive interpretation of Convention No. 87 by the principal judicial organ of the United Nations. 

The Court’s reasoning

The ICJ acknowledged that Convention No. 87 contains no express reference to the right to strike, but held that this silence does not exclude the issue from the treaty's scope. Reading Articles 2, 3(1), and 10 together, the Court concluded that the broad ordinary meaning of “activities” and “programmes” in Article 3(1) is capable of encompassing strike action. The Court held that the object and purpose of the Convention – guaranteeing freedom of association as a means of improving labour conditions - further supported that interpretation.

The Court also confirmed that statements of ILO supervisory bodies may be accorded “great weight” as a supplementary means of interpretation. Although those bodies differ from traditional expert treaty bodies, the Court held that they perform a functionally comparable role in monitoring the implementation of the Convention and noted the long-standing view of both bodies that Article 3 of Convention No. 87 protects the right to strike. The Court therefore rejected the Employers’ Group’s argument that the supervisory bodies had exceeded their mandate.

Four judges dissented. In broad terms, they objected that the majority had overstretched the text and purpose of Convention No. 87, treated freedom of association and the right to strike as insufficiently distinct, and placed undue weight on supervisory bodies which lack formal interpretive authority under the Convention. The majority was also criticised for, in substance, inverting the judicial process by reasoning towards a preferred human rights outcome, rather than interpreting the treaty according to ordinary principles of construction.

The UK position

The ICJ's opinion sits uneasily with the UK's domestic framework, which has never recognised a freestanding right to strike either at common law or in legislation. At common law, industrial action will ordinarily constitute a repudiatory breach of the employment contract, and a union calling or supporting such action may incur liability for inducing breach of contract and other economic torts. 

To allow industrial action, Parliament has instead conferred statutory immunities from tortious liability. The principal immunity is contained in section 219 of the Trade Union and Labour Relations (Consolidation) Act 1992 (TULRCA), which applies in respect of, but not limited to, the torts of inducing breach of contract, intimidation and simple conspiracy. However, section 219 remains subject to detailed statutory conditions and exclusions, including restrictions on secondary action and exclusions from protection for strikes intended to enforce trade union membership or impose union recognition requirements. 

The Institute of Employment Rights has described this reliance on statutory immunities from common law liability as “a very fragile basis on which to protect a human right in a modern human rights culture”, particularly because the immunities are “built on the shifting sands of the common law” and “can be undermined by the creation of new heads of liability which were not anticipated at the time the legislation was passed.” 

The statutory immunities model has been considered in the domestic courts, most notably in Secretary of State for Business and Trade v Mercer [2024] UKSC 12, where the Supreme Court held that section 146 TULRCA does not protect workers from detriment short of dismissal for taking part in lawful industrial action, and cannot be read compatibly with the European Convention on Human Rights (ECHR) so as to provide that protection. The incompatibility identified in Mercer was narrow but significant: domestic law provided no protection against sanctions short of dismissal imposed to deter trade union members from taking part in lawful strike action. The Court accordingly made a declaration that section 146 TULRCA is incompatible with Article 11 to the extent that it fails to provide that protection. Mercer demonstrates that, while Parliament may condition the protection of industrial action through a statutory scheme, that scheme must still provide effective protection where the absence of a remedy would make the Article 11 right practically ineffective. 

Statutory controls on industrial action have also been tightened in recent years by successive Conservative governments, particularly between 2010 and 2024. Ballot thresholds were introduced, including a 50 per cent turnout requirement and a further requirement in key public services that at least 40 per cent of those entitled to vote support the action. Maximum damages available against trade unions were increased and the Secretary of State was empowered to mandate minimum service levels across key sectors. However, the Labour government elected in 2024 marked a clear shift in direction. One of its first steps was to withdraw the previous Conservative administration’s ICJ submission, which had maintained that Convention No. 87 does not protect the right to strike. 

The Employment Rights Act 2025

That change in approach has continued with the Employment Rights Act 2025 (ERA). ERA introduced a wide-ranging package of industrial relations reforms, most of which took effect in February 2026. The new protection from detriment for workers participating in protected industrial action, which addresses the remedial gap identified in Mercer, is expected to come into force in October 2026. We consider the changes introduced by ERA in the article linked here.  

The ERA does not, however, create a freestanding right to strike. The framework continues to operate through statutory immunities from tortious liability, conditional upon compliance with detailed procedural requirements – an approach fundamentally distinct from the recognition of a positive right articulated by the ICJ. For instance, although ERA removed the 12-week cap on unfair dismissal protection for employees taking part in industrial action, that enhanced protection still only attaches to “protected” (i.e. lawful) industrial action within the meaning of TULRCA, leaving employees taking part in unofficial action unprotected from unfair dismissal. This underscores the broad theme of the UK framework - that strike action remains something conditionally tolerated where procedural requirements are met, rather than a recognised right in itself.

Implications for the UK

Whilst ICJ advisory opinions are authoritative on the interpretation of international law, the UK courts are not bound by them, and Convention No. 87 has not been incorporated into domestic law. 

Although the current Labour Government has stepped back from earlier Conservative administrations’ opposition to the protection of the right to strike, its submissions to the ICJ maintained that the right to strike “should be regulated at the national level”. That emphasis on national discretion is consistent with the Government’s approach of strengthening protections within the existing immunities framework, rather than replacing it with a freestanding statutory right. 

The opinion may therefore have more immediate practical significance in the UK through its potential influence on the European Court of Human Rights. In its interpretation of the ECHR, the ECtHR is required to take account of relevant rules of international law, and their interpretation by competent organs. In RMT v United Kingdom (National Union of Rail, Maritime and Transport Workers v United Kingdom [2014] ECHR 366), RMT argued that the UK’s prohibition on secondary action infringed Article 11 ECHR. The ECtHR acknowledged the ILO's criticism of the ban and noted that the UK was “one of a small group of European countries which adopted an outright ban on secondary strikes, at the far end of the spectrum”, but held the interference justified on the facts. The Court also emphasised that Article 11 should not be interpreted in a manner significantly narrower than prevailing international standards. Notably, the UK Government contended in that case that the ILO supervisory bodies lacked authority to give definitive interpretations of Convention No 87, and pointed to ongoing disagreement within the ILO as to the existence of a right to strike.

Clearly, the ICJ’s recent opinion weighs heavily against both propositions, clarifying the legal status of the right to strike and confirming that the views of ILO supervisory bodies should be accorded “great weight”.

Against that backdrop, the clearer position now established by the ICJ may narrow, to some extent, the margin of appreciation afforded to ECHR member states when restricting elements of the right to strike. The ICJ's opinion weakens the UK Government's defence in RMT - namely, that there was no settled international consensus on the existence of such a right. The ECtHR may therefore be less inclined to afford a wide margin of appreciation to states maintaining broad prohibitions on certain forms of industrial action. This, in turn, may give rise to renewed challenges to section 224 and related provisions of TULRCA, and, following the approach taken in Mercer, could see the UK courts being asked to interpret the legislation compatibly with Article 11, or to issue further declarations of incompatibility under the Human Rights Act.

More broadly, the opinion reinforces the trajectory of international and European jurisprudence towards recognising the right to strike as a core component of the freedom of association. While the UK's current immunities framework is unlikely to be displaced in the near term, the legal context in which it operates has shifted. Employers, trade unions, and policymakers should therefore anticipate continued scrutiny of restrictions on industrial action, with the ICJ's opinion likely to be cited in future litigation before both the domestic courts and Strasbourg.