The Supreme Court will consider whether to keep alive the largest job discrimination case in U.S. history, a lawsuit against Wal-Mart that grew from a half-dozen women to a class action that could involve billions of dollars for more than a half million female workers.

Wal-Mart is trying to halt the lawsuit, with the backing of many other big companies concerned about rules for class-action cases — those in which people with similar interests increase their leverage by joining in a single claim. Class actions against discount seller Costco and the tobacco industry are among pending claims that the high court’s decision might alter.

The suit against Wal-Mart Stores Inc. contends that women at Wal-Mart and Sam’s Club stores are paid less and promoted less often than men. The case the high court accepted on Monday will not examine whether the claims are true, only whether they can be tried together.

Estimates of the size of the class range from 500,000 to 1.5 million women who work or once worked for Wal-Mart.

Wal-Mart, based in Bentonville, Ark., is appealing a ruling by the 9th U.S. Circuit Court of Appeals in San Francisco that the class-action lawsuit could go to trial.

Tobacco giant Altria Corp., Bank of America Corp., Dole Food Company Inc., General Electric Co., Intel Corp., Pepsico Inc. and United Parcel Service Inc. are among the companies that also called for high court review of the case.