The U.S. Supreme Court will hear arguments tomorrow in a class action lawsuit filed by women who claim that Wal-Mart discriminated against them in the areas of pay and promotions. According to the women, men were routinely paid more money for the same or lesser work, and they were given more chances than women to be promoted.

The Supreme Court will not rule on the merits of the case but instead on whether the court can treat all women who might have been discriminated against as a single class. If not, then women would have to file separate, smaller lawsuits.

At stake is potentially billions of dollars that Wal-Mart would have to pay to more than one million women should the company lose the case.

Amy Sepinwall, Wharton professor of legal studies and ethics, suggests that this is “a classic case in which the law and common sense diverge: Suppose we learned that women constituted two-thirds of Wal-Mart’s low-level shift employees, but only 14% of its managers, who are generally promoted from the ranks of the shift employees. The disparity would at least raise a presumption of discrimination.” Those statistics, she notes, are provided by the plaintiffs and are contested by the company.

“Why weren’t more women being promoted, we might ask,” Sepinwall says, adding that “discrimination — however subconscious — would surely be a plausible response. If that way of thinking doesn’t seem compelling enough, substitute ‘African Americans’ for ‘women’ in the statistics quoted, and the intuitive force of the thought that there is at least a presumption of discrimination should be clearer still.” But the Supreme Court, she adds, “largely at Wal-Mart’s behest, has asked the parties whether the bald statistics are enough. Wal-Mart argues that it is misleading to generalize over employment practices at the company’s 3400 stores” where the women who are part of the lawsuit held a number of different kinds of positions.

Will the conservative tilt of the Supreme Court — a tilt which generally favors employers — be a factor in this case? “Conservative members of the court stand to be hostile to the contention that the class certification should be sustained,” says Sepinwall, citing two lines of precedent that provide an indication for how the court might view the current case.

First, notes Sepinwall, these Supreme Court justices “have [voiced] opposition to any kind of race-based classifications, whether these were intended to thwart or promote the interests of a racial minority. ‘Our Constitution is color-blind,’ Justice Scalia famously intoned, and one imagines that he would approach sweeping gender-based classifications in the same way.”

A second precedent for “divining the perspective of the Court’s conservative justices” is the Lilly Ledbetter case, according to Sepinwall. In that case, the plaintiff learned in 1998 that “her salary was on average $1,000 less per month than the salary of men who held the same position and were hired at the same time as her, in 1979. The five conservative justices on the Court denied Ledbetter’s employment discrimination claim on the grounds that it was untimely — the relevant employment decisions were made more than 180 days before she filed her discrimination complaint, and the applicable statute required that the adverse decision be made within 180 days of the filing of the complaint.”

The dissent argued that the Court “could instead have found that, with every pay period, [the company] carried its discrimination forward. In that way, the Court could have held that Ledbetter satisfied the 180-day requirement,” Sepinwall says, adding that President Obama apparently agreed with the dissent: The Lilly Ledbetter Fair Pay Act, which overturned the Court’s decision, was the first bill he signed into law.

The Ledbetter case is relevant here, she goes on, “because the majority’s ‘cramped’ reading of the statute — to quote the characterization Justice Ruth Ginsburg offered in her dissent — might well be indicative of a more general hostility to employment discrimination suits.”  

The women in the case, Dukes v. Wal-Mart Stores, are seeking back pay and punitive damages from the company.