The Constitution lets presidents make temporary appointments while the Senate is in recess but does not specify what a recess is or how long one must last before that power can be exercised.
That ambiguity, courtesy of the founding fathers, is helping fuel a battle between President Barack Obama and congressional Republicans over whether he had legally installed Richard Cordray on Wednesday to head the new Consumer Financial Protection Bureau, along with three others he named to the National Labor Relations Board.
At its heart, the dispute is a political one between a president seeking re-election as a populist protecting consumers and a GOP wary of federal agencies it considers too powerful. But it could come down to a legal battle in the courts as well.
Angry Republicans argue that the Senate _ which confirms or rejects most presidential nominations, but not recess appointments _ was not technically in recess when Obama made his appointments on Wednesday, though it has conducted no real work since before Christmas.
They note that Congress did not approve an adjournment resolution before lawmakers left town. In addition, they say, both chambers have held brief sessions about every three days, though they've not tackled any actual legislative business.
The White House says its lawyers believe the Senate is in recess. They say the non-business, "pro forma" sessions that Congress has periodically staged are solely an attempt to block presidential appointments and do not change the fact that the Senate is in recess.
Democrats have used the same tactic that Republicans are using now.
Late in Republican George W. Bush's presidency, the Democratic-led Senate began to punctuate its breaks with non-business sessions, preventing Bush from making any recess appointments from November 2007 through the end of his term, according to a December report by Congress' nonpartisan Congressional Research Service.
That report said the Department of Justice has offered varying views over the years about how long lawmakers must be away before a recess appointment may be made. But in 1993 under President Bill Clinton, a Justice brief implied that a president can make a recess appointment if a break by the Senate lasts more than three days, the CRS report said.
That brief cited a clause in the Constitution that forbids either chamber of Congress from adjourning for more than three days unless the other chamber has voted to let them do so.
In the past two decades, no appointments have been made during recesses of less than 10 days, the CRS report said. Prior to that, the report said, appointments have been made at least twice during recesses of three days or less, in 1903 and 1949.
Recess appointments are far from rare. Clinton made 139 and George W. Bush made 171 during their eight-year terms, according to the research service. So far, Obama has made 32.
Under the Constitution, recess appointments last until the end of the next session of Congress. Since congressional sessions generally begin on Jan. 3, Cordray's recess appointment _ and those of the three new members of the labor board _ could last through 2013.