Congress has held two hearings already on the cases of Ashcroft v. Iqbal and Bell Atlantic v. Twombly, which introduced a new “credibility” requirement in pleading standards that civil rights advocates and some Democratic lawmakers complain leaves the fate of discrimination victims to the prejudices of a particular judge assigned to the case. Now, instead of simply having to state clearly what the claims are, plaintiffs have to convince the judge that those claims are credible at the outset, before even having had an opportunity to collect evidence to support them.

While that pleases some conservatives who view most civil rights lawsuits with skepticism, civil rights experts say it rewards employers and others who discriminate but have learned to cover their tracks.

As the Times puts it today: “The practical impact in, say, an employment discrimination case is to disadvantage the wronged employee, who is unlikely to have access at the outset to the records needed to prove wrongful conduct.”

The Times cites John Payton, president of the NAACP legal defense fund, who recently testified that some of the landmark cases of the civil rights era might never have survived the Supreme Court’s new standard. In his written testimony submitted to the Senate Judiciary Committee earlier this month, Payton cites specific examples of potentially meritorious cases that didn’t survive the new standard because the plaintiffs couldn’t convince a skeptical judge that employment, voting or housing discrimination is “credible.”

As Sen. Sheldon Whitehouse (D-R.I.), a former U.S. Attorney, put it at that Senate hearing, “In my experience, misconduct is inherently implausible” because we generally expect people to act decently, fairly and lawfully.

Nadler’s legislation acknowledges the fact that sometimes, they don’t live up to that standard.

In concluding that a plaintiff claiming age discrimination must show not only that age was a motivating factor in the employer’s decision, but the determinative motivating factor, the court is essentially requiring the employee to produce direct evidence that the employer’s action was based only on age. In the past, because employers are careful to hide direct evidence of discriminatory motives, after a plaintiff had provided evidence of age discrimination the burden shifted to the employer to prove its legitimate reason for firing or demoting the older employee.

In this ruling, the high court appears to have just upended the prevailing understanding of employment discrimination law dating back to the case of Price Waterhouse v. Hopkins, a key Supreme Court ruling in 1989, and effectively pronounced that age discrimination is simply less important to remedy than race, gender, ethnic or disability discrimination.

Given how widespread layoffs of older employees are in this economy, the court just substantially undercut the only federal protection those employees have.

Justice John Paul Stevens, in his dissent, joined by Justices Ruth Bader Ginsburg, Stephen Breyer and David Souter (yes, another 5-4 decision), called the majority’s opinion “particularly inappropriate” given the “unambiguous history” of courts interpreting the application of the age discrimination law in the same way as other employment discrimination prohibitions.

“I disagree not only with the court’s interpretation of the statute, but also with its decision to engage in unnecessary lawmaking,” he wrote.

This afternoon, Sen. Patrick Leahy (D-Vt.) also weighed in on the decision with a statement.

“In the Supreme Court’s decision today, five justices acted to disregard precedent and ignore the plain reading and common understanding of the statute that Congress passed to protect Americans from discrimination based on their age,” he said, adding: “By disregarding congressional intent and the time-honored understanding of the statute, a five member majority of the Court has today stripped our most senior American employees of important protections.”