New rules strengthen protected industrial action, while creating fresh challenges for employers managing strikes and maintaining business continuity

The protections for those participating in industrial action have undergone a seismic shift in recent years, culminating in the changes introduced by the Employment Rights Act 2025 (ERA).

Since the early 1970s workers have had the right not to be subjected to detriment where the sole or main purpose was to prevent, deter or penalise membership (or non-membership) of a union, or participation in the activities of a union at “an appropriate time” (now section 146 of what is now the Trade Union and Labour Relations (Consolidation) Act 1992 (TULRCA)).

Critically, the framework adopted by parliament was essentially: if a worker was behaving lawfully, they could not be subjected to a detriment; but if a worker breached their contract by undertaking industrial action, then the protections did not apply.

This was confirmed by the Supreme Court in Secretary of State for Business and Trade v Mercer [2024] ICR 814. Ms Mercer went on strike and alleged her subsequent suspension from work was an unlawful detriment. The Supreme Court held section 146 did not apply as industrial action did not constitute the activities of a trade union “at an appropriate time”.

But Article 11 of the European Convention on Human Rights required the UK to afford appropriate and proportionate protection to Ms Mercer’s right to strike. The Supreme Court found that the lack of any protection for striking workers against detriment was in breach of Article 11.

The court made a declaration of incompatibility and sent the matter back to parliament to consider how a “fair balance” should be struck in affording appropriate protection to workers participating in industrial action.

Section 76 of the (ERA) addressed this by inserting new provisions at sections 236A–236D TULRCA granting the secretary of state powers to make regulations prohibiting detriments “of a prescribed description” for “the sole or main purpose of preventing or deterring the worker from taking protected industrial action, or penalising the worker for doing so.”

Following consultation, the government has published draft Protection Against Detriment (Industrial Action) Regulations 2026 due to come into force on 30 October 2026. The draft regulations took an expansive approach and prohibit “any detriment” done with the proscribed purpose, subject to expressly preserving the old common law rule that an employer may deduct pay from workers taking part in industrial action. If a worker goes on strike, they have no entitlement to be paid, but they are entitled not to be subjected to any other detriment.

Dismissal

Section 152 TURLCA provided a parallel protection against dismissal. A dismissal is automatically unfair where the reason for dismissal was union membership or participation in union activities at an appropriate time.

A complex scheme developed between the 1970s and 1990s to provide protection only in certain circumstances against dismissal for those participating in industrial action. Those participating in unofficial industrial action had very limited protections against dismissal (section 237 TURLCA). Those participating in “protected” industrial action had protections against selective dismissals of only some striking workers or within a “protected period” of 12 weeks following the industrial action (sections 238-238A TURLCA).

Section 77 ERA 2025 has amended section 238A TURLCA to cut through some of the complexity in removing the protected period for those participating in “protected” industrial action. With effect from 18 February

2026, it is automatically unfair to dismiss an employee at any time for the reason that they took part in protected industrial action.

Blacklisting

A further tool in the union’s armoury – and often used in conjunction with trade union detriment or dismissal cases – is the prohibition in the Employment Relations Act 1999 (Blacklisting) Regulations 2010 on the creation of a list of union members for the purposes of discriminating against them. These regulations will be expanded under section 67 ERA 2025.

Under regulation 9, employers are prohibited from subjecting a worker to a detriment for a reason related to a blacklist. In Morais v Ryanair DAC [2025] ICR 863, the Court of Appeal confirmed that striking workers are protected by the regulations, whether or not the strike was “protected” industrial action.

Updated by the ERA in February, the new section 3(2A) of the Employment Relations Act 1999 enables regulations prohibiting not just the creation but also the use of lists which contain details of members of trade unions or those participating in union activities for the purposes of discrimination.

In 2027 we anticipate the regulations will prohibit employers using lists created for legitimate reasons (ie, payroll or attendance lists) to target trade union members or those engaged in union activities including striking.

The Blacklisting Regulations present a further tripwire for how employers manage industrial action and the need to avoid creating or using any list for the purpose of identifying and discriminating against those participating in industrial action.

Effect of the changes

The ERA has significantly enhanced the protections afforded to those participating in “protected” and properly authorised industrial action. Although an employer can continue to deduct pay correlating to industrial action, it must not subject its workers to any other detriment or dismiss them because of their participation.

This is likely to create a headache for employers taking contingency measures to address industrial action. We expect to see detriment claims brought in respect of enhanced training and other benefits provided to workers roped-in to cover striking staff and not offered to those participating in industrial action. The preservation of the “no work, no pay” rule is sensible in principle but may be difficult to apply when, for example, making performance or attendance-related pay or bonus awards. There may be disputes about whether it is a detriment to deduct full pay following a refusal to accept partial performance.

The key to unlocking many disputes will be the reason for the employer’s action. Tribunals have long recognised that a detriment or dismissal may occur in the context of industrial action but not because of the industrial action. There may be other factors, related to industrial action, which result in a detriment or dismissal which is properly separable to the industrial action itself. Two obvious categories spring to mind.

First, “wholly unreasonable, extraneous or malicious acts” (Morris v Metrolink [2019] ICR 90, CA) done by a worker in the context of industrial action may nonetheless be proper grounds for detriment or dismissal.

Second, contingency steps taken by an employer to cope with industrial action, such as additional training or overtime for non-striking workers, or removing access to the workplace, will be lawful provided it is not done for the sole or main purpose of preventing, deterring, or penalising those participating in industrial action but instead for the purpose of ensuring business continuity or addressing safety and security issues.

The difficulty is that the reason for the employer’s action normally has to be tested at trial; the parties will ordinarily have to bear the emotional and financial strain of litigation. Nonetheless, it is important for employers to be clear in their decision-making and the reasons for their decisions, and to have these properly recorded.