"They are notoriously difficult to prove," says Joseph Turco, a specialist in discrimination lawsuits at the firm Spar & Bernstein in New York. To prove the cases, the plaintiffs will be allowed to present circumstantial evidence. But the employer is allowed to pull out bad performance reviews. "The burden is then back on the plaintiff to show the reason given is pretext," says Mr. Turco. But he says society has become more attuned to employers' efforts to hide discrimination. "Our generation gets it," he says.
Moreover, the sheer size of the case could present problems for both sides.
Stepping up the size of the case to a class action "gives them much greater leverage, because obviously the case is that much bigger," says Judy Malone, an employment law attorney at Palmer & Dodge in Boston. "But it also complicates the case. They've gone from having to prove the case of how many individual plaintiffs they have to representing a class of 1.6 million people. It's going to be a very big case to try to manage on both sides."
She adds: "One of the concerns in the case is that this includes all of the Wal-Mart companies, which may include other related companies. And the argument is these are not monolithically managed, so it's really difficult to lump them all together."
US District Judge Martin Jenkins in San Francisco took nine months to decide whether to expand the lawsuit to include virtually all women who work or have worked at Wal-Mart. In a hearing last September, company attorneys urged Jenkins to allow so-called mini-class action lawsuits targeting each outlet.
Jenkins ruled that a 1964 congressional act passed during the civil rights movement prohibits sex discrimination and that giant corporations are not immune.
In addition, the judge said, the plaintiffs presented sufficient anecdotal evidence to warrant a class-action trial.
Judge Jenkins cited "statistics which show that women working at Wal-Mart stores are paid less than men in every region ... that the salary gap widens over time."