A man pushes carriages outside of a Walmart store in Valley Stream, N.Y.
A man pushes carriages outside of a Walmart store in Valley Stream, N.Y. - 
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Kai Ryssdal: The class action case in question this morning at the Supreme Court wasn't just your run-of-the-mill lawsuit. Had the justices agreed with a lower court ruling, it would have been the biggest such case ever. A million and a half women across the country -- current and former employees of Walmart -- would've been eligible. It was a gender discrimination suit. And I say was, because it's now in the past tense. Customers of tobacco, oil and pharmaceutical companies -- among many many others -- have used class actions successfully. But now, things could change after this ruling.

Our Washington Bureau Chief John Dimsdale has the story.

John Dimsdale: Organizers of this class action claimed Walmart's pay and promotion policies in every store nationwide favored men. But the Supreme Court decided the small group of women who filed the class action didn't share the same status, or circumstances, with a million or more other Walmart workers.

Michael Droke is a labor lawyer with Dorsey & Whitney.

Michael Droke: The court says that there really has to be some common issue of fact, and in particular a common injury.

Today's ruling, he says, will shield large corporations from massive class action lawsuits that would be costly to defend.

Brendan Burke: It is unquestionably harder for large groups of plaintiffs to bring these types of cases now.

Brendan Burke is a labor discrimination consultant. He still expects to see smaller, more targeted class action lawsuits from corporate employees.

Burke: Instead of one large giant lawsuit in this case, a number of smaller lawsuits, let's say filed on behalf of you know store managers or assistant store managers. So you'll see a number of smaller lawsuits with more commonality.

Burke says smaller class actions are usually easier to prove since judges and juries can see how corporate wrongdoing hurts individuals.

In Washington, I'm John Dimsdale for Marketplace.