E. Desmond Hogan, a lawyer for the black agents, said the agents were “shocked but not surprised by the late production of significant evidence of racism at high levels in the Secret Service.”

“The government’s delay,” Mr. Hogan said, “follows a pattern of the Secret Service stonewalling plaintiffs and ignoring court orders, depriving African-American agents of the fundamental evidence of race discrimination that is key to their claims.”

The lawsuit, which has dragged on through years of litigation, was filed in 2000 by 10 black agents who charged that they were unfairly denied promotions. The agency employs about 3,200 agents, about 10 percent of whom are black.