A lawsuit against America's largest employer is serving as a reminder that concerns about gender discrimination persist, despite four decades of focus on equal workplace rights.
Wal-Mart hasn't been found guilty of sex discrimination - and it may never be, in part because class-action cases on this issue are often settled out of court.
But the very fact that such a large case against the retailer has made it this far - with a federal appeals court giving the go-ahead Tuesday for a class-action lawsuit involving more than 1.5 million women - puts the issue back in the national spotlight more than at any other time in recent years.
The case revolves around wage issues - equal pay for equal work. But it also alleges that Wal-Mart shortchanged female employees on opportunities for promotion.
It's that issue - the proverbial glass ceiling - that studies find is the most intractable gender inequity in US industries today, despite the gains women have made since the equal-rights era.
"There actually has been tremendous progress.... Women are so much more visible," says Vicky Lovell of the Institute for Women's Policy Research, a nonpartisan research group in Washington. "Yet we do see [discrimination] continuing."
The issue matters not just for women but the whole economy, because the underlying question is whether businesses are making the most productive use of the talent available. Gender discrimination represents a failure involving nearly half the workforce.
Women face a significant gap with men in promotion opportunities, according to research published last year by Cornell University economists Francine Blau and Jed DeVaro.
Their data covered 3,500 employers in four US cities. The study found that 10.6 percent of men had received promotions during a four- year period versus 7.6 percent of women - a gap of 3 percentage points.
Even after sifting out a range of possible explanations, including education, skills, and seniority, that gap narrowed a bit, but the promotion rate remained 2.2 percentage points apart.
Interestingly, this study, which drew on survey data from the 1990s, found no solid evidence that those women who were promoted got smaller pay raises than men.
But some experts say that important pay gaps remain - albeit not as wide as those that existed four decades ago.
"Comparable worth ... remains a very big question," says Ms. Lovell. She says this isn't just getting the same pay for the same job, but equalizing pay scales across different careers that are comparable in skills and other respects.
In the Wal-Mart case, the plaintiffs allege more basic concerns that the company failed to pay the same rate for women as men in the same jobs.
"I was layaway manager, getting $7.50 an hour" in Vacaville, Calif., says Patricia Surgeson, one of the plaintiffs in the lawsuit. When the …