WASHINGTON — Democrats have reversed the partisan imbalance on the federal appeals courts that long favored conservatives, a little-noticed shift with far-reaching consequences for the law and President Obama’s legacy.
For the first time in more than a decade, judges appointed by Democratic presidents considerably outnumber judges appointed by Republican presidents. The Democrats’ advantage has only grown since late last year when they stripped Republicans of their ability to filibuster the president’s nominees.
Democratic appointees who hear cases full time now hold a majority of seats on nine of the 13 United States Courts of Appeals. When Mr. Obama took office, only one of those courts had more full-time judges nominated by a Democrat.
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.
The full appeals court agreed this month to hear Halbig v. Burwell, a case that could unravel the system of federal insurance exchanges established by the Affordable Care Act. Before Democrats curtailed Republicans’ right to use filibusters, which they accomplished by rewriting Senate rules through a maneuver known as “the nuclear option,” the District of Columbia court was dominated by judges who were appointed by Republican presidents. Today it has four Republican appointees and seven Democratic appointees, four of whom Mr. Obama picked.
With control of the Senate at stake in November’s midterm elections, the success of Democrats in reshaping the courts is a reminder of the subtle power that the majority party has even in a moribund Congress. Republicans, who have watched with growing alarm as the Obama nominees passed through the Senate, have begun raising the issue as they try to win six seats they need to take the majority.
“It’s no surprise that President Obama has been able to transform the ideological makeup of the courts — that happens when you have six years to pick judges and your party controls the Senate,” said Edward Whelan, the president of the Ethics and Public Policy Center, who was a senior official in the Justice Department under President George W. Bush. “The best way for conservative voters to prevent further damage to the courts is to swing the Senate to Republican control in the elections this November.”
Though the Obama administration was well on its way to leaving a lasting liberal legacy on the federal bench before Senate Democrats curbed the filibuster’s power, the rules change sped up the confirmation process. Today, the number of circuit judges appointed by Republican presidents is 77, compared with 95 by Democratic presidents, according to statistics kept by Russell R. Wheeler of the Brookings Institution.
At the beginning of Mr. Obama’s first term, the picture was reversed: 99 appointed by Republicans and 65 by Democrats. Of course, a president’s political affiliation ultimately has no bearing on how a judge decides cases. History is full of examples when partisans were disappointed by a judge who turned out not to be the loyal ally they expected, like David H. Souter, the liberal-leaning former Supreme Court justice nominated by the first President George Bush. The Supreme Court remains the only court that Republicans can still try to shape through using the filibuster. When Democrats changed the Senate rules to lower the threshold for most confirmations, they left one exception: The minority party still can require a 60-vote majority to confirm a justice.
The quickening pace of judicial confirmations is all the more surprising considering that at the end of his first term Mr. Obama was lagging well behind his two most immediate predecessors, Mr. Bush and Bill Clinton, in leaving an imprint on the courts. In part because his administration placed a higher priority on passing legislation like the Affordable Care Act than on confirming judges, Mr. Obama was slow to make nominations.
And early in his first term, the president purposely stayed away from nominating people who could be pilloried in the confirmation process as overly ideological and further strain partisan tensions in the Senate.
But as Senate Republicans started routinely using the filibuster to thwart Obama nominees as part of their broader strategy to stymie the president’s agenda, the White House and Senate Democrats shifted tactics. The result was not just to strong-arm nominations through the filibuster rules change that infuriated Republicans, but also to make sure left-leaning judges, some of them young and who could serve for decades, were nominated.
“There were always politics in court appointments and in the functioning of the judiciary,” said Senator Richard Blumenthal, Democrat of Connecticut and a member of the Judiciary Committee. “But the rawness and the starkness of the political clashes in the courts has highlighted the need to have people there that are of an ideological like mind.”
Kathryn Ruemmler, Mr. Obama’s White House counsel until last spring, said Republicans, to their credit, had always been strategic about judicial appointments and the confirmation process. “Mitch McConnell cares about judges, and for good reason,” she said, referring to the Senate Republican leader. “Everybody understands how important the Supreme Court is. They don’t always understand how important the lower courts are.”
Major pieces of Mr. Obama’s agenda are all but certain to face legal tests in the months and years to come.
Among the most important to the administration are proposed climate change regulations to cut pollution from power plants, a matter that could end up before the District of Columbia court. A dozen states have already filed a lawsuitagainst the Environmental Protection Agency seeking to block some of the new proposals.
House Republicans have also filed a lawsuit contending that the president exceeded the limits of his authority when he delayed putting into place certain parts of the Affordable Care Act. That case, too, could end up at the District of Columbia court.
The imprint of the Obama judges is already being felt. In July, when the United States Court of Appeals for the Fourth Circuit issued an opinion declaring Virginia’s same-sex marriage ban unconstitutional, the author was an Obama appointee, Henry F. Floyd. That court now has 10 full-time judges appointed by Democratic presidents and five who are Republican appointees. When Mr. Obama took office, the court had a majority of Republican appointees.
A version of this article appears in print on September 14, 2014, on page A1 of the New York edition with the headline: Building Legacy, Obama Reshapes Appellate Bench.