The shift, one of the most significant but unheralded accomplishments of the Obama era, is likely to have ramifications for how the courts decide the legality of some of the president’s most controversial actions on health care, immigration and clean air. Since today’s Congress has been a graveyard for legislative accomplishment, these judicial confirmations are likely to be among its most enduring acts.

“With all the gridlock, it is forgotten that one of the most profound changes this Congress made was filling the bench,” said Senator Charles E. Schumer, Democrat of New York, who led the push with the White House last summer to force the confirmation of three nominees to the United States Court of Appeals for the District of Columbia Circuit after Republicans blocked them. “This will affect America for a generation, long after the internecine battles on legislative issues are forgotten.”

With so many of the administration’s policies facing legal challenges, the increased likelihood that those cases could end up before more ideologically sympathetic judges is a reassuring development to the White House. Nowhere has this dynamic been more evident than at the District of Columbia court, which is considered the second most important appeals court in the nation, after the Supreme Court.