The U.S. Constitution empowers the president to fill vacancies for those federal positions that require Senate confirmation when the Senate is not in session. Article II, Section 2, Clause 3 reads:
The President shall have Power to fill up all Vacancies that may happen during the Recess of the Senate, by granting Commissions which shall expire at the End of their next Session.The President can act to fill a vacant office, but the appointee serves only until the end of the congressional session. At that time the appointee either leaves office or stands for formal confirmation by the Senate. This provision was clearly necessary in the early days of the nation when Congress was absent from the capital for long periods and transportation was often undependable. However, in more recent times the recess appointment was been used as a tool by the President to overcome actual or anticipated Senate refusal to approve his nominations. In 1961, John F. Kennedy used the recess appointment to gain a seat on the federal bench for Thurgood Marshall, who would later become the first black Associate Justice on the U.S. Supreme Court (1967). Kennedy figured correctly that once Marshall was seated, public opinion would help to assure his eventual confirmation by the Senate. In more recent times, Bill Clinton used a recess appointment in naming James Hormel as ambassador to Luxembourg (June 1999) and George W. Bush did likewise in appointing Charles Pickering to the U.S. Court of Appeals (January 2004). The party out of power often describes presidential use of the recess appointment as being disrespectful of Senate prerogatives and “unconstitutional;” the former may be true in some instances, but not the latter.