No doubt emblematic of his entire time in office, President Barack Obama will sign his first piece of legislation today–a labor law that overturns a Bush-era Supreme Court decision.

Lilly Ledbetter, who was the subject of that Supreme Court ruling, will be there when Obama inks the Lilly Ledbetter Fair Pay Act into law.

The legislation reverses the court’s decision in the Ledbetter case that the 180-day statute of limitations on pay discrimination cases starts ticking when the initial decision is made to pay unfairly. The Fair Pay Act amends the 1964 Civil Rights Act and mandates that the statute starts ticking again every time a paycheck is issued to the victim.

(Pay discrimination is defined as an employee’s being paid less for the substantially same job and same set of job responsibilities, figuring in length of service, etc., based on age, race, gender and factors besides experience.)

Opponents fear that this will just open up the spigot for lawyers to march an endless stream of employees into court and win two years of backwardly adjusted pay.

They’re probably right.

N.B.: Catch this, the law is worded to “take effect as if enacted on May 28, 2007.” This is curious for a couple of reasons. First, I believe there’s a Constitutional ban on ex post facto laws (backdated laws), and this date is one day before the Supreme Court heard the Ledbetter case. Evidently, it’s been so written as to enable Lilly to go back to the Supreme Court and reopen her case. If so, I hope the court rules that the start date is unconstitutional.