— were a sham that was intended to prevent him from filling seats on the NLRB.

The justices rejected that argument Thursday.

Justice Stephen Breyer said in his majority opinion that a congressional break has to last at least 10 days to be considered a recess under the Constitution.

Neither house of Congress can take more than a three-day break without the consent of the other.

The issue of recess appointments receded in importance after the Senate's Democratic majority changed the rules to make it harder for Republicans to block confirmation of most Obama appointees.

But the ruling's impact may be keenly felt by the White House next year if Republicans capture control of the Senate in the November election. The potential importance of the ruling lies in the Senate's ability to blockappointments.

The lower court held that the only recess recognized by the Constitution is the once-a-year break between sessions of Congress. It also said that only vacancies that arise in that recess could be filled. So the high court has left open the possibility that a president, with a compliant Congress, could make recess appointments in the future.

Justice Antonin Scalia, writing for himself, Chief Justice John Roberts and Justices Samuel Alito and Clarence Thomas, said he would have upheld the lower court's reasoning. He said Thursday's decision means "the abolition of the Constitution's limits on the recess-appointment power."

Obama has made relatively few recess appointments, 32 in his five-plus years in office, according to the Congressional Research Service. President George W. Bush made 171 such appointments over two terms and