WASHINGTON — 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.

“The decision is novel and unprecedented,” Carney said. “It contradicts 150 years of practice by Democratic and Republican administrations.”

Under the court’s decision, 285 recess appointments made by presidents between 1867 and 2004 would be invalid.

The Justice Department hinted that the administration would ask the Supreme Court to overturn the decision, which was rendered by three conservative judges appointed by Republican presidents. “We disagree with the court’s ruling and believe that the president’s recess appointments are constitutionally sound,” the statement said.

The court acknowledged that the ruling conflicts with what some other federal appeals courts have held about when recess appointments are valid, which only added to the likelihood of an appeal to the high court.

“I think this is a very important decision about the separation of powers,” said Carl Tobias, a constitutional law professor at Virginia’s University of Richmond. “The court’s reading has limited the president’s ability to counter the obstruction of appointments by a minority in the Senate that has been pretty egregious in the Obama administration.”

The ruling also threw into question the legitimacy of Obama’s recess appointment of Richard Cordray to head the Consumer Financial Protection Bureau. Cordray’s appointment, made on the same date, has been challenged in a separate case.

Carney insisted the court’s ruling affects only a single case before the labor board and would have no bearing on Cordray’s appointment. Obama on Thursday renominated Cordray for the job.

The case challenging the recess appointments was brought by Noel Canning, a Washington state bottling company that claimed an NLRB decision against it was not valid because the board members were not properly appointed. The D.C. Circuit panel agreed.

Obama made the recess appointments after Senate Republicans blocked his choices for an agency they contended was biased in favor of unions. Obama claims he acted properly because the Senate was away for the holidays on a 20-day recess. The Constitution allows for such appointments without Senate approval when Congress is in recess.

But during that time, GOP lawmakers argued, the Senate technically had stayed in session because it was gaveled in and out every few days for so-called pro forma sessions.

GOP lawmakers used the tactic — as Democrats had done in the past — specifically to prevent the president from using his recess power to install members to the labor board and the consumer board. They had also vigorously opposed the nomination of Cordray.

The three-judge panel flatly rejected arguments from the Justice Department’s Office of Legal Counsel, which claimed that the president has discretion to decide that the Senate is unavailable to perform its advice and consent function.

“Allowing the president to define the scope of his own appointment power would eviscerate the Constitution’s separation of powers,” Chief Judge David Sentelle wrote in the 46-page ruling. He was appointed by President Ronald Reagan.

The court ruled that during one of those pro forma sessions on Jan. 3, 2012, the Senate officially convened its second session of the 112th Congress, as required by the Constitution.

Sentelle’s opinion was joined by Judge Thomas Griffith, appointed to the court by President George W. Bush, and Karen LeCraft Henderson, who was appointed by President George H.W. Bush.

“With this ruling, the D.C. Circuit has soundly rejected the Obama administration’s flimsy interpretation of the law, and (it) will go a long way toward restoring the constitutional separation of powers,” said Sen. Orrin Hatch, R-Utah.

GOP House Speaker John Boehner welcomed the ruling as “a victory for accountability in government.”

If the ruling stands, it would invalidate more than 600 board decisions issued over the past year. It also would leave the five-member labor board with just one validly appointed member, effectively shutting it down. The board is allowed to issue decisions only when it has at least three sitting members.

Obama used the recess appointment to install Deputy Labor Secretary Sharon Block, union lawyer Richard Griffin and NLRB counsel Terence Flynn to fill vacancies on the labor board, giving it a full contingent for the first time in more than a year. Block and Griffin are Democrats, while Flynn is a Republican. Flynn stepped down from the board last year.

All three vacancies on the labor board had been open for months before Obama acted to fill them.

Sen. Tom Harkin, D-Iowa called the ruling “a radical departure from precedent” and argued that Obama had no choice but to act.

“Throughout his presidency, Republicans have employed unprecedented partisan delay tactics and filibusters to prevent confirmation of nominees to lead the NLRB, thus crippling the board’s legal authority to act,” Harkin said.

If Obama’s recess appointment of Cordray to the newly created consumer board is eventually ruled invalid, it could nullify all the regulations the consumer board has issued, many of which affect the mortgage business.