Employers could face workplace discrimination claims from former staff years after they have left the company following a landmark ruling in the Supreme Court this week.

The case involved more than 170 women who worked for Birmingham City Council, mostly as cleaners, cooks, caterers and care staff, who claimed they were paid less than their male colleagues while employed at the local authority.

They said that workers in traditionally male-dominated jobs such as refuse collection had been handed bonuses by the council, while those in mainly female roles of a similar level were not.

Between 2007 and 2008 Birmingham City Council paid out thousands of pounds to women bringing similar compensation claims, but only those who did so within six months of leaving their jobs – the time limit placed on cases to be taken to an employment tribunal.

However, those who were initially denied compensation took their case to the civil courts, which have a much longer six-year statute of limitations.

The women won their case at both the High Court and Court of Appeal, but Birmingham Council’s lawyers took the case to the Supreme Court, where they argued only an employment tribunal, and not the civil courts, have jurisdiction over such matters.

However, the five-judge panel ruled 3-2 in favour of the former workers.

The ruling effectively means that employees can lodge workplace discrimination claims up to six years after leaving their job, rather than the previous time limit of six months.

It also opens up the possibility of a flood of new claims against employers by former workers.

The law firm Leigh Day & Co, which represents the women, described the judgment as “the biggest change to equal pay legislation since it was introduced in 1970, with huge implications for thousands of workers”.

However, speaking to the Guardian, a spokesperson for the Local Government Association said local councils should be fairly well protected from a rash of claims thanks to the progress they have made in increasing equality in the workplace in recent years.

“Claimants can only pursue back pay that falls within six years of starting any action and councils have made significant progress on equal pay, with the vast majority of inequality issues in local government remedied more than six years ago,” they commented.