June has been in recent years the time for disappointing Supreme Court rulings, and this year is no different. In a major win for corporate America, the Court effectively threw out a large sex discrimination case against Wal-Mart.

The implications for class-action lawsuits in general could be even more enduring. The 9th Circuit Court of Appeals ruled that well over one million female Wal-Mart employees could join a lawsuit that accused the retailer of wage and promotion discrimination against women. The Supremes overturned that, saying unanimously that all those employees could not join the lawsuit. It was on the broader question of class-action lawsuits in general, however, that there was an ideological split.

The justices divided 5-4 on another aspect of the ruling that could make it much harder to mount similar class-action discrimination lawsuits against large employers.

Justice Antonin Scalia’s opinion for the court’s conservative majority said there needs to be common elements tying together “literally millions of employment decisions at once.”

But Scalia said that in the lawsuit against the nation’s largest private employer, “That is entirely absent here.”

Justice Ruth Bader Ginsburg, writing for the court’s four liberal justices, said there was more than enough uniting the claims. “Wal-Mart’s delegation of discretion over pay and promotions is a policy uniform throughout all stores,” Ginsburg said.

That’s a huge corporate victory, allowing them to abuse their employees that much more with one less consequence. Class-action suits are one way to keep employers in line, because the knowledge of the size of their exposure will discourage them. Now, workers systematically screwed by their corporate parents have less access to the courts, less ability to make a systematic claim.

The Administration likes to talk about the Lily Ledbetter Fair Pay Act. But this blow by the Supreme Court necessitates more law in that arena. The courthouse door has again been blocked to regular workers at the bequest of corporate interests. The Roberts courts’ nearly unblemished corporate record continues.

UPDATE: NOW President Terry O’Neill has a sharp reaction.

“With this decision, the Supreme Court has assisted Wal-Mart in its efforts to systematically dole out promotions and pay raises on the basis of sex. The law calls that illegal discrimination, but this Court has turned its back on the more than million women who only sought simple justice,” said NOW President Terry O’Neill. “The women of Wal-Mart deserve respect and fair treatment, and we will continue to stand up for their rights.”

She adds that one problem for the women of Wal-Mart was that they weren’t unionized, so they had a barrier to collectively bargain for their rights in the workplace.