NEW YORK (CNNMoney.com) -- Wal-Mart has asked the Supreme Court to stop a massive gender discrimination suit that has dragged on for years, the company said Wednesday. The suit is the largest class-action employment discrimination case in U.S. history.
The suit accuses Wal-Mart of discouraging the promotion of female store employees to managerial positions. It also alleges women were paid less than men across all job positions. The suit seeks changes in the company's internal procedures and more than $1 billion in back pay, as well as punitive damages.
The case, known as Dukes v. Wal-Mart, includes the 1.5 million women who have worked at any of the company's 4,000 retail stores nationwide since Dec. 26, 1998.
The suit was originally filed in 2001, and Wal-Mart (WMT, Fortune 500) has voiced complaints since then over the merit of the case. Several courts have ruled the case should go to trial, most recently April's ruling from the Ninth Circuit U.S. Court of Appeals in San Francisco.
Wednesday's announcement said Wal-Mart had filed a petition to the Supreme Court, asking it to review the Ninth Circuit's ruling.
"This case involves important issues about class action procedure and Title VII," Wal-Mart's statement said. The retailer claims the Ninth Circuit's ruling "contradicts numerous decisions of other appellate courts and even the Supreme Court itself."
"It is important to remember that the Ninth Circuit's opinion dealt only with class certification, not with the merits of the lawsuit," the statement added.
The plaintiffs' co-lead counsel, Joseph Sellers of Cohen Milstein Sellers & Toll, released a statement later in the day saying the ruling followed standards that courts have adhered to for decades.
"Only the size of the case is unusual, and that is a product of the size of Wal-Mart and the breadth of the discrimination we detected and documented," Sellers said.
If Dukes reaches the Supreme Court, the case could set a precedent for employment discrimination class actions.