The claimants sought to appeal a decision by the Employment Appeal Tribunal concerning their claims for equal pay.

The claims were brought by (for the most part) female employees carrying out different jobs in supermarkets who say they are being paid less than men carrying out work of equal value in other roles in warehouses or distribution centres operated by the same supermarket chain.

The case involved 22 multiple claims presented in respect of 5497 claimants. The number of differing job roles performed by the various claimants within a single form ET1 varied from 8 to 175.

Rule 9 of the Employment Tribunals Rules of Procedure 2013 provides that two or more claimants "may make their claims on the same claim form if their claims are based on the same set of facts". The respondent employer argued the claimants doing different jobs could not base their claims on the same set of facts and therefore could not join their claims in a single claim form.

The claimants argued even if this was irregular, the initial tribunal was correct in exercising its discretion under Rule 6 to waive the irregularity.

The Court of Appeal held the supermarket’s shop workers, who are mostly female, can compare their role with higher paid warehouse staff, who are mostly male, for the purposes of their equal pay claim.

The Court ordered the case to be remitted to the tribunal to proceed on its merits.
https://www.bailii.org/ew/cases/EWCA/Civ/2019/8.html

Beth Hale, general counsel at CM Murray, said although the ruling was “vitally important for the future of equal pay claims” and represented a major victory for the Asda employees, the equal pay claim had not yet been tested – yet alone lost – by the retailer. “[This is] by no means the end of the road,” she said.
 
“In most cases, employees will be allowed to compare themselves with any employee of the same employer. They will then need to demonstrate that their roles are of equal value and that there is not a reason other than sex for the disparity in pay.”
https://www.peoplemanagement.co.uk/news/articles/supermarket-workers-win-equal-pay-battle