Based on the Ledbetter decision, defense lawyers around the country are busy preparing motions to dismiss individual claims. Louis A. Rodriques, co-chair of the labor and employment group at Bingham McCutchen, is one of them.

His law firm, which represents companies sued by workers, is already trying to get several cases thrown out of court based on the Ledbetter decision.

He said that many courts allowed pay discrimination claims to proceed long after an allegedly discriminatory pay decision, on the theory that each new paycheck with lower pay "was a kind of separate wrong."

There may be a certain logic in that. Rodriques noted that pay decisions in the workplace are often closely guarded secrets, but pointed out that the court's decision does hew to precedent, which is also important.

In her dissent, Justice Ginsburg cited a law review article suggesting that one-third of private-sector employers have adopted rules prohibiting employees from discussing their wages with one another.

Rodriques said he basically agrees with Ginsburg but believes the majority rendered the right decision in putting pay discrimination claims on the same footing with cases involving demotions and terminations, in which workers were required to file claims within the tight 180-day timeline. (In the numerous states that have a fair employment agency, including employment hubs such as New York and California, the rule is 300 days.) 

"The fact is, women have just as much of a difficult time learning whether they are being promoted or demoted or terminated as they do about pay decisions," Rodriques said. He added that he thinks creative lawyers will seek to work around the Supreme Court decision on behalf of plaintiffs.