In this post, Liz Jackson, Trainee Solicitor, and Max Wiktorsson, Associate, in the Employment Team at CMS preview the decision awaited from the Supreme Court in Secretary of State for Business and Trade v Mercer. The appeal is due to be heard by the Supreme Court on 12-13 December 2023.

Under the Trade Union and Labour Relations (Consolidation) Act 1992 (“TULRCA”), s. 146, workers are protected against detriments falling short of dismissal related to taking part in the activities of an independent trade union at an appropriate time. The scope of “trade union activities” in that provision has been interpreted as not including industrial action.

Issues before the Supreme Court

The issues before the Supreme Court are:

  • whether taking part in industrial action is an activity protected by TULRCA, s. 146;
  • if it is not, whether that is a breach of ECHR, art 11 (freedom of assembly and association);
  • if a breach of ECHR, art 11 is established, whether TULRCA, s.146 can be interpreted under the Human Rights Act 1998 (“HRA”), s. 3, in a way that is compatible with the ECHR;
  • if it cannot, whether the Supreme Court should make a declaration of incompatibility pursuant to the HRA, s.4.

The Facts

Fiona Mercer (“Mrs Mercer”), a support worker at Alternative Future Group Ltd (“the Company”), was at the relevant time a workplace representative for her trade union, UNISON. Mrs Mercer helped plan and organise strike action between 2 March and 14 May 2019 regarding a pay dispute. The Company suspended her on 26 March 2019. The Company said that the reasons for her suspension were that she had abandoned her shifts on two occasions and spoken to the press without authorisation and in a manner that conveyed confidential information and was considered likely to bring the Company into disrepute.

In her complaint to the Employment Tribunal, Mrs Mercer claimed that in breach of s. 146, she had been subjected to a detriment by the Company when it suspended her. The Company’s response form asserted that the suspension and disciplinary proceedings were unrelated to any trade union activities, but also that taking part in industrial action could not be an activity protected by s. 146.

The issues before the Supreme Court, and the lower courts, are divorced from the underlying facts of this case. There have been no findings of facts in this case, this section is included for contextual background.

The Law


Part III of TULRCA concerns rights in relation to union membership and activities.

S.146 states that a worker has the right not to be subjected to any detriment by their employer for the sole or main purpose of preventing or deterring the worker from taking part in the activities of an independent trade union at an appropriate time. “An appropriate time” means a time outside the worker’s working hours or a time within the worker’s working hours if the employer has consented to it.

S. 152, provides corresponding protection against dismissal (as opposed to detriment short of dismissal). S.152 gives employees the ability to claim automatic unfair dismissal if the principal reason for their dismissal was that they had taken part or proposed to take part in the activities of an independent trade union at an appropriate time.

Part V of TULRCA deals with industrial action more broadly, and also contains provisions about unfair dismissal complaints where industrial action is taken. Dismissals due to taking part in official industrial action, is dealt with under ss. 238 and 238A, as opposed to dismissals due to taking part in the activities of an independent trade union, which, as set out above, are dealt with under s. 152.


Art 11 states that everyone has the right to freedom of peaceful assembly and to freedom of association with others, including the right to form and to join trade unions for the protection of their interests. No restrictions can be imposed on this right other than those necessary in a democratic society.

Decision of the Employment Appeal Tribunal (“EAT”)

The EAT held that the Employment Tribunal was correct in finding that as a matter of ordinary construction, s. 146 does not provide protection to workers engaged in industrial action and thus s.146 as currently construed violates art. 11.

However, the EAT disagreed with the Employment Tribunal that a wider interpretation of s. 146 would go against the grain of TULRCA. The EAT held that there is nothing to suggest the grain of the legislation is to exclude protection against detriment for those participating in industrial action. The EAT suggested that the very fact that dismissal for participation in industrial action is protected under s.238 whilst those taking part in official strikes have no equivalent protection for detriment short of dismissal, is an anomaly in the legislation.

The EAT held that it was possible to construe s. 146 compatibly with art 11 by adding an additional limb to the definition of “appropriate time” in section 146(2), namely “(c) a time within working hours when he is taking part in industrial action”.

Decision of the Court of Appeal

The Court of Appeal agreed with the lower courts that s. 146 does not provide protection to workers engaged in industrial action. It held that the failure to give legislative protection against any sanction short of dismissal for official industrial action against the employees who take it may put the UK in breach of art. 11 if the sanction is one which strikes at the core of trade union activity.

However, the Court of Appeal disagreed with the EAT and held that the effect of the attempt to interpret s. 146 by adding an additional sub-clause would result in impermissible judicial legislation and not interpretation as sanctioned by s. 3. Noting that this is a sensitive issue and one for Parliament to address, the Court of Appeal restored the original decision by the Employment Tribunal.

The Court of Appeal also found that it would not be appropriate to grant a declaration of incompatibility in this case where there is a lacuna in the law rather than a specific statutory provision which is incompatible, noting that the extent of the incompatibility is unclear and the legislative choices are far from being binary questions.


Until the EAT’s decision in this case, s. 146 was widely interpreted as not extending to workers who go on strike, meaning that employers could consider taking action short of dismissal against striking employees. Overturning the EAT’s decision, the decision of the Court of Appeal returns to that previous legal position. However, it is noteworthy that the Court of Appeal agreed with both the Employment Tribunal and the EAT that the current level of protection for employees is unsatisfactory and potentially breaches their human rights under the ECHR.

The Supreme Court’s decision is eagerly awaited by trade unions and employers with trade union relationships. It is hoped that the decision will provide clarity on this important issue.

It also worth noting that the appeal to the Court of Appeal in Ryanair DCA v Morais EA-2021-000275 (“Ryanair”) has been stayed pending the judgment of the Supreme Court. Ryanair involves similar issues to Secretary of State for Business and Trade v Mercer but also includes related claims under the Employment Relations Act 1999 (Blacklists) Regulations 2010 (SI 2010/493).