The court threw out a class action in which six plaintiffs who complained of discrimination at Walmart had sought to represent a group of current and former female employees estimated to number up to 1.5m.

The case was of vital importance to business because it was the first time in more than a decade that the court had ­considered the standards that plaintiffs needed to meet to mount class actions.

The US Chamber of Commerce had warned that if the case was allowed to go ahead it would unleash an “avalanche” of class action litigation, potentially hobbling business with a range of employment, antitrust and product liability lawsuits.

Ted Boutrous, Walmart’s lawyer, said the ruling would be “very helpful in bringing back sanity to class action law in all different types of areas”.

Joseph Sellers, the plaintiffs’ lawyer, said the court’s decision had “reversed about 40 years of jurisprudence”, a reference to previous cases that he said had been endorsed by lower courts.

He said the case, which dates back 10 years, was not over and that the women were determined to pursue their claims in smaller or individual cases.

Walmart, which employs more than 2m people worldwide, was accused of paying women less than men and of passing them over for promotion in the US.

The case symbolised the opposition generated by Walmart’s rise to dominance in the US retail market.

The retailer said it was pleased with the court’s decision, which “effectively ends this class action lawsuit”.

In overturning the ruling of a lower court, the Supreme Court said the plaintiffs had failed to identify a common Walmart ­policy that led to discrimination, which could have explained why their experiences could be extrapolated across the workforce.

The workers “provide no convincing proof of a company-wide discriminatory pay and promotion policy”, wrote Justice Antonin Scalia for five members of the court. The justices were unanimous on some parts of the case and divided on others.

Brad Seligman, another lawyer for the plaintiffs, said his team was exploring how they could reformulate the class action on a smaller scale.

“This case is not over. Walmart is not off the hook. It’s really important that the women of Walmart don’t give it up hope,” he said.