President Barack Obama violated the Constitution when he bypassed the Senate last year to appoint three members of the National Labor Relations Board, a federal appeals court ruled Friday in a far-reaching decision that could severely limit a chief executive's powers to make recess appointments.

The decision of the U.S. Court of Appeals for the D.C. Circuit marked a victory for Republicans and business groups critical of the labor board. If it stands, it could invalidate hundreds of board decisions over the past year, including some that make it easier for unions to organize.

When Obama filled the vacancies on Jan. 4, 2012, Congress was on an extended holiday break. But GOP lawmakers gaveled in for a few minutes every three days just to prevent Obama from making recess appointments. The White House argued that the pro forma sessions — some lasting less than a minute — were a sham.

The court rejected that argument, but went even further, finding that under the Constitution, a recess occurs only during the breaks between formal year-long sessions of Congress, not just any informal break when lawmakers leave town. It also held that presidents can bypass the Senate only when administration vacancies occur during a recess.

White House press secretary Jay Carney said the administration strongly disagrees with the decision and that the labor board would continue to conduct business as usual, despite calls by some Republicans for the board members to resign.