Lilly Ledbetter worked for nearly twenty years at the Goodyear Tire plant in Gadsden, Alabama. She became a supervisor at the plant and filed suit in 1998 after learning that she had been paid hundreds of dollars less per month than even the lowest paid man (a relatively new hire) who was doing her same job. This comes as no surprise to working women, who even after the 'seniority' argument that had been made during the 1970's and 1980's as to why men were typically paid more has played itself out, still see that women are paid only $.78 per hour for every dollar a man earns for doing the same job.
After a series of victories in the lower courts, the Eleventh Circuit court reversed the lower court decisions, and when it went to the Supreme Court Ledbetter lost last year on a 5-4 vote. Though the Supreme Court agreed that she did have both identical job titles and duties to men who were being paid a lot more than she was, they argued that she was only entitled to additional back pay for 180 days prior to the date of her filing the suit and could not challenge decisions that had been made before that even though the discriminatory pay rates had been going on for years without her knowledge (and her fruitless attempt to get the problem fixed internally at Goodyear worked against her because it delayed her filing the suit.) The focus of the suit is what is known as 'paycheck accruel,' a longstanding precedent in which the clock on filing a discrimination case resets with every paycheck. The Supreme Court ruling upholding the eleventh circuit essentially voided that provision and therefore ruled that only the 180 day limit set under Title VII applied.
The pay difference that she experienced over years, and which many, many women still suffer from is exacerbated because it compounds into lower Social Security after retirement.
Last year after the Supreme Court decision, Congress tried to pass the Ledbetter Fair Pay Act which stipulates that women who can prove that they were discriminated against at work are entitled to up to two years of back pay differential to make up the difference, and more importantly specifically writes 'paycheck accruel' into law. The bill was blocked by a Republican filibuster (and it became an issue that Barack Obama made some ground on during the campaign since John McCain had made a speech opposing it, and Obama aired a commercial featuring Lilly Ledbetter that may have helped him re-open the gender gap that McCain had closed a bit when he picked Sarah Palin.)
This year it passed, with unanimous support from Senate Democrats, plus five Republicans-- significantly including all four of the Republican women in the Senate (and two of them, Lisa Murkowski and Kay Bailey Hutchison, are considered conservative). House Republicans were House Republicans, with only three voting in favor.
President Obama has now signed the law, the first piece of legislation he has signed that was passed by the new Congress. Besides equal pay for women, it represents a direct and specific repudiation of the Supreme Court, essentially restoring the law back to what lower courts had held, but now spelled out and codified as Federal law.