Case note prepared by the Thompsons Solicitors LLP Trade Union Law Group 


The Supreme Court has ruled unanimously that section 146 of the Trade Union and Labour Relations (Consolidation) Act 1992 (“TULRCA”) is incompatible with British citizens’ right to freedom of association under the Human Rights Act 1998 and the European Convention on Human Rights. 




In the case of Secretary of State for Business and Trade v Mercer [2024] UKSC 12 (link here), a panel of five Supreme Court judges were asked to determine whether the law preventing employers from subjecting workers to detrimental treatment to deter or prevent them from or penalise them for taking part in “trade union activities” also afforded protection to employees participating in lawful strike action.  


Ms Mercer was employed by Alternative Future Group Limited as a support worker in the care sector. She took part in lawful strike action and conducted various press interviews regarding the trade dispute. Her employer then made a decision to suspend her.  


Ms Mercer brought a claim to the Employment Tribunal that she had suffered detrimental treatment for the sole or main purpose of preventing or deterring her from, or penalising her for, taking part in the activities of an independent trade union under s.146 TULRCA. However, her employer argued that the definition of trade union activities under s.146 TULRCA is limited to activities that take place during “an appropriate time” and the statute makes clear that this means either at a time outside of working hours or a time agreed between the employer and employee for the employee to undertake union duties (also known as “facility time”). Therefore, s.146 TULRCA, did not afford her protection as industrial action occurs during working hours and without the employer’s agreement. The employer also argued that “trade union activities” for the purposes of s.146 TULRCA did not cover strike action, a proposition supported through existing case law and the fact that, TULRCA drew a clear distinction between trade union activities which were governed by Part III of the statutory provisions whereas industrial action (and the much more limited protection from dismissal only) was governed by Part V. Therefore, including industrial action as a trade union activity under Part III would be inconsistent with a fundamental feature of the legislation. 


As a consequence, the Employment Tribunal decided it was necessary to determine as a preliminary issue whether s.146 TULRCA provides protection for detriment short of dismissal where workers have taken lawful industrial action. The Employment Tribunal held that it did not and rejected Ms Mercer’s claim. The Employment Appeal Tribunal reversed this decision, finding that taking industrial action was a trade union activity and used its interpretative powers under the Human Rights Act 1998 to “read in” to s.146 protection for workers participating in industrial action by amending the definition of “appropriate time” to include all time within working hours when a worker is taking part in industrial action as opposed to only something done in a worker’s own time or where the worker has express consent from the employer to do the activity. It contended that construing s.146 TULRCA in the conventional way violated Article 11 


The employer appealed to the Court of Appeal and the Secretary of State joined proceedings as an intervener. The Court of Appeal reversed the decision of the Employment Appeal Tribunal, finding against Ms Mercer. The Court held that it was not possible to “read in” to s.146 protection against a detriment for participating in industrial action. The Court of Appeal also declined to exercise its power to declare that s.146 was incompatible with the right to freedom of association, as enshrined in the Human Rights Act 1998 and Article 11 of the European Convention on Human Rights. This was because the Court considered that it could only make a declaration where there was a specific law in place that conflicted with the Convention, and that it could not do so where, as was the case here, there was merely a lacuna in the law (that is, it cannot declare that a gap in the law is incompatible with the European Convention). 


Supreme Court Decision 


The Supreme Court in its judgment has now concluded that it is able to make a declaration of incompatibility (given its view s.146 could not be “read down” in way which would make it compatible with Article 11 by using its interpretative obligations pursuant to s.3 of the Human Rights Act 1998) where there was a gap in the law that fails to afford adequate protection.  The Court acknowledged and endorsed the fundamental human right to take industrial action and the fact that the right to freedom of association is devoid of substance without that right. It found that the interference with Ms Mercer’s right to freedom association (and the right to strike) was not because of a general gap in the law, but rather from the deficiency of the drafting of s.146 TULRCA. That is, s.146 was the “only provision which limits the common law in this context” and that its deficiencies were such that it “has the implicit effect of legitimising sanctions short of dismissal imposed on workers for participation in a lawful strike” and therefore the state was in breach of its positive obligation to protect Article 11 rights. Whilst the making of a declaration of incompatibility remained discretionary, the Supreme Court felt that it was appropriate in this case to make such a declaration.  


The effect of the declaration of incompatibility is not to overturn s.146, as the Supreme Court does not have the power to overrule Parliament. Instead, the declaration acts as an invitation to Parliament to amend the law in this area given it is a signatory to the convention. 


Whilst Parliament is under no obligation to act, this is a significant victory for UNISON and the whole trade union movement. The highest court in the land has ruled that UK strike laws breach the European Convention on Human Rights by giving insufficient protection to workers taking industrial action. This is a key recognition by the Supreme Court of the right to strike, and of the legal protection which must be given to trade unions and workers taking part in it. It is imperative that the law is now reconsidered to give workers adequate protection when they participate in lawful industrial action having regard to the jurisprudence of the European Court of Human Rights. This is in line with the state’s positive obligation to safeguard the fundamental rights of trade union members.