The Supreme Court has blocked Tesco from appealing a key ruling in a long-running equal pay claim brought by more than 16,000 shop workers.

Tesco is one of several UK supermarkets caught in a legal battle over allegations that it underpays its store workers, mainly women, compared with distribution centre workers, who are mostly men.

The case, launched in 2018 by claimant-focused law firms Harcus Parker and Leigh Day, now involves thousands of retail employees in separate cases against Asda, Next, Sainsbury’s, Morrisons, and the Co-Op. It is reportedly worth a potential £4bn.

In the case against Tesco, the claims were divided into three stages, but the back-and-forth stems from the Employment Tribunal deciding to use generic training documents, rather than individual daily duties, to define ‘work’ at the hearings.

Tesco appealed through multiple courts to stop the Tribunal from using this definition. Both the Employment Appeal Tribunal and the Court of Appeal partially allowed Tesco’s appeals, but both rejected its main argument that the Tribunal’s overall methodology should be overturned.

The retail giant sought to appeal to the Supreme Court, but the UK’s top court rejected the case earlier this month and refused its application.

As a result, the case will proceed to trial under the Employment Tribunals’ established methodology for defining ‘work’.

Kiran Daurka, employment partner at Leigh Day, said: “This is a significant outcome for the 16,000 Tesco workers we represent and brings Tesco’s challenge on this issue to an end.” He added, “We remain focused on securing equal pay for our clients in the wider litigation.”

Tesco was approached for comment.

Next’s recent dodge in its equal pay case

Last month, retail giant Next won an appeal in its equal pay case, allowing it to pay warehouse workers more than shop-floor staff, and warned that its defeat “would have represented a hammer blow to retail employment in the UK”.

This follows a 2024 Employment Tribunal ruling that the FTSE giant failed to show that paying its sales consultants, most of whom are women, lower hourly rates than staff in its male-dominated warehouses was not sex discrimination.

The retailer was on the line for a £30m payout before it appealed.

But the Employment Appeal Tribunal overturned the landmark decision, citing recruitment and retention pressures that do not apply to sales workers.