As noted here and here, the Supreme Court has ruled that the women of the class action discrimination lawsuit don’t have enough in common to constitute a class for this purpose. A crucial part of the reasoning behind this seems to be the claim that there was nothing systematic involved in denying women promotions and pay increases: these decisions were devolved to individual managers, and the corporation had a clear anti-discrimination policy. So it must have been just a bunch of individual decisions– no reason to believe there’s a pattern.
But there’s a nice argument from Nelson Lichtenstein that this is not the case: Walmart required managers to work 50 hour weeks on a regular basis, and 80-90 hour weeks occasionally. It also demanded that nearly everyone promoted to managerial ranks move to a different store, often hundreds of miles away. All this, quite obviously, disadvantages women. The idea that policies like this unfairly disadvantage women will be a familiar thought to feminist philosophers. Susan Moller Okin and Joan Williams discuss this, and it would count as discrimination under MacKinnon’s Dominance conception. I’m pretty sure it would also count as Indirect Discrimination under UK and EU law. And it’s definitely a pattern, so should have been enough to ground a class action suit.