Union membership, AI hiring tools and monitoring: UK protection from refusal, detriment and dismissal

Recruitment software can screen applications, monitoring tools can log who attends meetings or uses which channels, and scoring systems can feed decisions on shifts, pay and redundancy. If any of these picks up union membership or union activity and the employer acts on it, the Trade Union and Labour Relations (Consolidation) Act 1992 gives job applicants, workers and employees in Great Britain a route to an employment tribunal. This page sets out the core protections. It is for workers, employees, representatives and employers.

The short answer: it is unlawful to refuse someone employment because they are, or are not, a union member (s137). A worker has the right not to be subjected to a detriment by the employer for the sole or main purpose of deterring or penalising union membership, taking part in union activities at an appropriate time or using union services (s146). Dismissing an employee, or selecting them for redundancy, for those reasons is automatically unfair, with no qualifying period (ss152 to 154).

Refusal of employment

It is unlawful to refuse a person employment because they are, or are not, a member of a trade union, or because they are unwilling to accept a requirement to join, leave or stay out of a union, or to make payments if they are not a member (s137(1)). A person unlawfully refused employment can complain to an employment tribunal (s137(2)).

Refusal is defined widely. It covers an employer who refuses or deliberately omits to entertain and process an application or enquiry, causes the applicant to withdraw it, refuses or deliberately omits to offer the job, makes an offer on terms no reasonable employer wishing to fill the post would offer, or makes an offer and then withdraws it (s137(5)). An application quietly dropped by a screening process is therefore within the section if membership was the reason. The section applies in the same way to an employment agency acting, or purporting to act, for an employer (s137(8)). If a job advertisement indicates that the job is open only to members or non-members, an applicant who does not meet that condition and is refused is conclusively presumed to have been refused for that reason (s137(3)).

Detriment during employment

A worker has the right not to be subjected to any detriment as an individual by any act, or deliberate failure to act, by the employer, if it takes place for the sole or main purpose of (s146(1)):

• preventing or deterring them from being or seeking to become a member of an independent trade union, or penalising them for doing so;
• preventing or deterring them from taking part in the activities of an independent trade union at an appropriate time, or penalising them for doing so;
• preventing or deterring them from making use of trade union services at an appropriate time, or penalising them for doing so; or
• compelling them to be or become a member of a union.

An appropriate time is outside working hours, or a time within working hours when, under arrangements agreed with or consent given by the employer, it is permissible to take part in union activities or use union services (s146(2)). Using union services includes consenting to the union raising a matter on the worker's behalf, and penalising a worker because their union raised a matter for them counts as penalising them for using union services (s146(2A) and (2B)).

The right belongs to workers, not only employees. Where the worker is an employee and the detriment amounts to dismissal, the dismissal rules below apply instead (s146(5A)). On a complaint, it is for the employer to show the sole or main purpose for which it acted or failed to act (s148(1)). An employer that relies on a monitoring dashboard or a ranking model should be able to explain what the tool measured and why the decision was taken.

Dismissal and selection for redundancy

For unfair dismissal purposes, dismissal of an employee is regarded as unfair if the reason, or the principal reason, was that the employee was or proposed to become a member of an independent trade union, had taken part or proposed to take part in its activities at an appropriate time, had made use or proposed to make use of union services at an appropriate time, or was not a member or refused to become or remain one (s152(1)). Where a union raised a matter on the employee's behalf as a member and that was one of the reasons for dismissal, the reason is treated as using union services (s152(2B)).

Where the principal reason for dismissal was redundancy, the dismissal is unfair if the same circumstances applied equally to others in similar positions in the same undertaking who were not dismissed, and the principal reason the employee was selected was one of the union reasons in s152(1) (s153). This matters when a scoring matrix or an automated ranking is used to choose who goes; see redundancy selection.

The qualifying period and the upper age limit for unfair dismissal do not apply to a dismissal that is unfair under s152 or s153 (s154). For the general rules, see unfair dismissal.

Time limits

A complaint about refusal of employment must be presented within six months beginning with the date of the conduct complained of, or within a further reasonable period if the tribunal is satisfied that this was not reasonably practicable (s139(1)). For a deliberate omission to process an application or to offer employment, the date is the end of the period within which it was reasonable to expect the employer to act (s139(2)(b)). A detriment complaint must be presented within six months beginning with the date of the act or failure, or the last of a series of similar acts or failures, with the same extension where it was not reasonably practicable (s147(1)). The six month period was substituted with effect from 1 October 2026 by the Employment Rights Act 2025 and SI 2026/954, which has transitional provisions, so check which period applies to conduct before that date. Both periods can be extended to allow for Acas early conciliation (ss139(4) and 147(4)); see Acas early conciliation.

Practical steps

• Applicants: keep the advertisement, the application and every message from the employer or agency, with dates. Note if an application was never acknowledged or an offer was withdrawn.
• Workers and employees: keep a record of union activity, meetings and any matter your union raised for you, and of the decisions that followed, such as lost shifts, lower scores or missed overtime. Ask your union representative for help early, as the time limits are short.
• Employers: check that screening, monitoring and scoring tools do not take in union membership, attendance at union meetings or contact with a union as an input, directly or through a proxy. Lists of union members or activists compiled for screening are covered by the ban on blacklisting. Keep the reasons for decisions on hiring, shifts, pay and redundancy, since on a detriment complaint the employer has to show its purpose. Members' time off for union activities is covered in trade union time off, and how union agreements deal with AI in AI and unions.

These provisions extend to England, Wales and Scotland. This page is general information on the law in Great Britain as at 1 November 2026, not legal advice.