What is a recess appointment?
Article II, Section 2 of the Constitution grants the President the authority to:
Nominate, and by and with the Advice and Consent of the Senate, . . . appoint Ambassadors, other public Ministers and Consuls, Judges of the supreme Court, and all other Officers of the United States, whose Appointments are not herein otherwise provided for, and which shall be established by Law.
Under normal circumstances, when a vacancy occurs in one of these posts, the President nominates an individual to fill the position and the Senate then votes to either confirm or reject the President's nominee. However, the Framers anticipated that vacancies would occur while the Senate was not in session. The Constitution provides that (also in Article II, Section 2): 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.
While this provision is fairly straightforward, it has produced several differences of opinion between the Congress and the President. How many days must the Senate fail to convene for it to lapse into a recess? Does a position have to become vacant during a Senate recess for a valid recess appointment to be made or does the position simply have to remain vacant during the recess? Instead of allowing the Court to settle these disputes, the Congress and the President have generally agreed to work together to solve them. This makes sense because neither side has a particularly clear interest in forcing the issue. If the President tries to force recess appointments on the Senate, thus circumventing the normal "advice and consent" process, the Congress can refuse to appropriate funds to pay the salaries of the appointees. The Senate might also take the extraordinary measure of blocking future nominations to "teach the President a lesson." Furthermore, if the Senate took a hostile approach to all recess appointments, it would essentially have to remain in session all of the time--an inefficient solution, to say the least.
Currently, the President and Congress generally adhere to a procedure for recess appointments that minimizes the potential for interbranch conflict. If the President wishes to make a recess appointment or appointments, he generally sends a list of persons to be appointed to members of the Senate shortly before or during a recess. If Senators express serious concerns about a nominee, the President will likely hold off on the appointment until the Senate is back in session and the normal procedure can be followed.