Blacklisting, vetting databases and AI screening: the UK ban on lists of union members

Background checks, vetting services and recruitment software all build and share records about people. If a record exists to flag who has been in a union or taken part in union activities, so that employers or agencies can screen them out, it may be a prohibited list under the Employment Relations Act 1999 (Blacklists) Regulations 2010. This page sets out what the Regulations ban in Great Britain and the claims they give. It is for job applicants, workers, employers, agencies and anyone who supplies vetting data.

The short answer: no person may compile, use, sell or supply a list of union members or people who take part in union activities that is compiled for employers or employment agencies to discriminate in recruitment or in the treatment of workers (reg 3). A person refused a job or agency services, or subjected to a detriment, for a reason relating to such a list can complain to an employment tribunal (regs 5, 6 and 9). Dismissal for such a reason is automatically unfair (ERA 1996 s104F).

What counts as a prohibited list

A prohibited list is a list that contains details of people who are or have been union members, or who are taking part or have taken part in union activities, and that is compiled with a view to being used by employers or employment agencies for discrimination in recruitment or in the treatment of workers (reg 3(2)). Discrimination means treating a person less favourably than another on grounds of union membership or activities (reg 3(3)). Use of a list includes use of the information in it (reg 2). The test turns on what the list contains and why it was compiled, not on its format, so a spreadsheet, a database field or a flag in a screening tool can all qualify.

There are exceptions (reg 4). They include supplying a list without knowing, and without being reasonably expected to know, that it is a prohibited list; compiling, using or supplying one to expose a breach, where no one's details are published without their consent and it is justified in the public interest; requirements for union experience or union membership for certain posts and union offices; use required or authorised by law or a court order; and use for legal proceedings or legal advice on compliance with the Regulations.

Refusal of a job or of agency services

A person can complain to an employment tribunal if an employer refuses to employ them for a reason relating to a prohibited list, and the employer either breaches reg 3 itself or relies on information supplied in breach of reg 3 that it knows or ought reasonably to know was supplied in breach (reg 5(1)). Refusal includes refusing or deliberately omitting to process an application, causing the person to withdraw it, not offering the job, offering unreasonable terms, or making and then withdrawing an offer (reg 5(2)). The same applies to an employment agency that refuses its services, or does not provide them on the same terms as to others (reg 6).

The burden can shift. If there are facts from which the tribunal could conclude, without another explanation, that the employer or agency breached reg 3 or relied on information supplied in breach, the tribunal must find that it did unless the employer or agency shows that it did not (regs 5(3) and 6(3)).

Detriment and dismissal

A person can complain to an employment tribunal if their employer, by an act or deliberate failure to act, subjects them to a detriment for a reason relating to a prohibited list, on the same conditions about breach or reliance (reg 9). Where the detriment is the dismissal of an employee, the unfair dismissal rules apply instead (reg 9(3)). An employee is regarded as unfairly dismissed if the reason, or principal reason, for the dismissal relates to a prohibited list and the employer breached reg 3 or relied on information it knew or ought reasonably to have known was supplied in breach (ERA 1996 s104F). See unfair dismissal and, for dismissal or detriment because of union membership or activities more generally, union membership protection.

Remedies and time limits

On a successful refusal complaint, the tribunal makes a declaration and may order compensation, which can include injury to feelings, and recommend action to reduce the adverse effect (reg 8). In the legislation.gov.uk text on 1 November 2026, reg 8 sets a minimum award of £5,000 before adjustments and a maximum of £65,300; check the current figures. A breach of reg 3 is also actionable in the courts as a breach of statutory duty, where the court can order the defendant to stop and award damages (reg 13).

A refusal complaint must be presented within six months beginning with the date of the conduct, and a detriment complaint within six months of the act or failure, or the last of a series (reg 7(1) and reg 10(1)). In both cases the tribunal may hear a late complaint if it is just and equitable to do so, and the periods can be extended for Acas early conciliation; see Acas early conciliation. The six month periods were substituted from 1 October 2026 by SI 2026/758, which has transitional provisions, so check which period applies to earlier conduct.

Practical steps

• Applicants and workers: keep the advertisement, your application, every message from the employer or agency and any vetting or background check you were asked to consent to. Note dates, since the time limits are short.
• Employers and agencies: check what any vetting service or screening tool draws on. Do not compile or use records of union membership or activity for recruitment or treatment of workers, and be able to show where third-party data came from, because relying on information you ought reasonably to know was supplied in breach is enough for a claim.
• Vetting and data suppliers: do not compile, sell or supply lists of union members or activists for employers or agencies to screen people.

For wider rules on automated hiring, see AI in hiring. These Regulations 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.