LITTLE ROCK, Ark. - Six women sued Wal-Mart Stores Inc., alleging the retail giant discriminated against them in pay and promotions because of their gender. Now, company lawyers are trying to keep another 1.5 million women from being added to the complaint.

The plaintiffs want the suit elevated to class status, opening it to a wide range of current and former female workers at the nation's largest private employer.

U.S. District Judge Martin Jenkins is to hear their arguments Friday in San Francisco. A ruling is not expected for months.

Bentonville-based Wal-Mart argues the class would be too big to manage and claims the plaintiffs did not use commonly accepted statistical methods in compiling their numbers. Also, the company argues that the scope of the proposed class is without precedent.

Lawyers for the women, who claim they were harassed or denied opportunities by individual Wal-Mart stores, say the corporation is at fault. But the company says managers are free to make their own decisions and the plaintiffs can't show enough commonality to warrant class status.

Each side has attacked the other's interpretation of how personnel decisions involving women are made at Wal-Mart.

Wal-Mart spokeswoman Mona Williams says the company's promotion rates of women shows that Wal-Mart has "more opportunities for women than any other employer in the country." The plaintiffs say Wal-Mart only started keeping those statistics as the evidence-gathering period in the lawsuit was coming to a close in January.

Regardless of the hearing's outcome, plaintiff attorney Brad Seligman of Berkeley, Calif., says the loser will request an appeal hearing before the 9th U.S. Circuit Court of Appeals.

The lawsuit was filed in 2001, and listed Betty Dukes, Micki Earwood, Kimberly Miller, Stephanie Odle, Sandra Stevenson and Patricia Surgeson as plaintiffs. Friday's hearing centers only on whether others should be added.

Perry Binder, an assistant professor of legal studies at the Robinson College of Business at Georgia State University in Atlanta, said the judge's ruling will be critical for both sides.

"Any time a class gets certified, there is power in unity. Any time a class-action suit is not certified, then you have to have individual plaintiffs filing individual lawsuits," Binder said.

"This is the biggest leverage point - which party's got the leverage is the biggest (aspect) of a lawsuit," he said.

The plaintiffs describe several examples of discrimination, including a required meeting for female managers that was held at a strip club. Another meeting allegedly occurred at a Hooters restaurant, which is known for scantily clad female servers.

"The key is whether there is a systematic, across-the-company level of gender discrimination," Binder said. "What the plaintiffs have to prove is that this truly is a (men's) club."

Wal-Mart acknowledges some isolated cases have occurred in which women were not treated fairly. But it denies any systematic discrimination among its stores and says no legal basis exists to certify the class.

Binder said the plaintiffs have to come up with "smoking gun documents."

"The key for the plaintiffs is to find documents that link Wal-Mart to nationwide discrimination," Binder said, making it clear he doesn't know whether such documents exist.

Binder said the plaintiffs have to subpoena electronic archives of internal e-mails, computer files, instant messages and the like.

"This is going to be a very costly proposition. This is what litigation is in the 21st century - searching computer banks for so-called deleted e-mails," Binder said.

Binder said the lawsuit apparently has not done any damage to Wal-Mart - yet. In fact, Wal-Mart could use the court action to bolster its reputation.

"If they actually win this lawsuit, the positive spin from Wal-Mart could be spun that way," he said.

Williams said the lawsuit is the most critical piece of litigation the retailer now faces.

The world's largest company by sales, Wal-Mart faced 6,649 active lawsuits as of July 11, she said. The vast majority were tort and individual employment matters.

The complaint in San Francisco for class status is different.

"I would say it is the most important because of the sheer scope of it. It is No. 1 on our radar screen right now," Williams said.

"We are a very decentralized company and store managers have a lot of discretion when it comes to decision making," she added. "With more than 3,000 stores, there are occasional errors in judgment."

Williams said that any worker who perceives unfair treatment can use Wal-Mart's open-door policy.

Seligman said the opposite is true. Store visits by Wal-Mart executives, real-time computer analysis, Bentonville training sessions for far-flung store managers all telegraph a central point of control.

"For class-certification purposes, is there a common dispute here? Clearly, there is," Seligman said.