Like its fellow ratings agencies, Standard & Poor’s once seemed virtually immune from liability for doling out AAA ratings to doomed-to-fail securities in the run-up to the subprime meltdown. A proposed class action brought by investors in S&P parent McGraw Hill Companies Inc. was a case in point: A federal judge tossed the case back in March 2012, and the U.S. Court of Appeals for the Second Circuit briskly affirmed the dismissal last August.

Nevertheless, plaintiffs lawyers at Robbins Geller Rudman & Dowd, citing a claim filed earlier this year against S&P by the U.S. Justice Department and other new evidence, attempted a last-ditch bid to revive their failed shareholder suit. But Southern District Judge Sidney Stein (See Profile) rejected the effort in a ruling issued on Tuesday, concluding it was too little too late.