"Pay is a complicated thing."

Linda Greenhouse elegantly explains a difficult Supreme Court case about the lingering effects of long-ago job discrimination:

Is each new paycheck, reflecting a salary lower than it would have been without the initial discrimination, a recurring violation that sets the [statute of limitations] clock running again? Or does the passage of time, without fresh acts of intentional discrimination, render the initial injury a nonevent in the eyes of the law?...

[T]he E.E.O.C. ... has long applied what is known as the “paycheck accrual rule,” under which each pay period of uncorrected discrimination is seen as a fresh incident of discrimination. So although the 180-day limit applies to discrete actions like a discriminatory refusal to hire or failure to promote, it does not, in the view of the federal agency charged with administering the statute, prevent lawsuits for the continuing effects of past discrimination in pay.

But the Bush administration has disavowed the commission’s position....

When Justice Antonin Scalia asked, “Why should we listen to the solicitor general rather than the E.E.O.C.?”...

Justices Ruth Bader Ginsburg and Stephen G. Breyer appeared most sympathetic to Mr. Russell’s argument. Justice Breyer commented at one point that “there will be probably a significant number of circumstances where a woman is being paid less, and all she does is for the last six months get her paychecks and she doesn’t really know it because pay is a complicated thing.” It could take “even a year for her to find out,” he said.

Chief Justice John G. Roberts Jr. appeared the most skeptical, several times raising the question of how employers could shoulder the burden of defending long-ago pay decisions.

“It could be 40 years, right?” Chief Justice Roberts asked Mr. Russell, adding, “I mean, if it happened once 20 years ago, you have a case that you can bring” under the plaintiff’s analysis.

The case is Ledbetter v. Goodyear Tire and Rubber Company Inc.