"… If any Bill shall not be returned by the President within ten Days (Sundays excepted) after it shall have been presented to him, the Same shall be a Law, in like Manner as if he had signed it, unless the Congress by their Adjournment prevent its Return, in which Case it shall not be a Law. "
If the President does not sign the bill within the required time period, the bill becomes law by default. However, the exception to this rule is if Congress adjourns before the ten days have passed and the President has not yet signed the bill. In such a case, the bill does not become law; it is effectively, if not actually, vetoed. If the President does sign the bill, it becomes law. Ignoring legislation, or "putting a bill in one's pocket" until Congress adjourns is thus called a pocket veto. Since Congress cannot vote while in adjournment, a pocket veto cannot be overridden (but see below). James Madison became the first president to use the pocket veto in 1812.
Mason's Manual says:
"When legislation is passed so late in the session that the session ends prior to the expiration of the time the governor is given to act on bills, the governor has the power to withhold action on the bill and let it die from failure to approve it. This is called the pocket veto.
In December 2007, President George W. Bush pushed the pocket veto into murky waters by claiming that he had pocket vetoed H.R. 1585, the "National Defense Authorization Act for Fiscal Year 2008, even though the House of Representatives had designated agents to receive presidential messages before adjourning. The bill had been previously passed by veto-proof majorities in both the House and the Senate. If the President had chosen to veto the bill, he would have been required to return it to the house whence it originated, which, in this case, was the House of Representatives. The House then could have voted to override the veto, and the Senate could then do likewise. In the event that each house had voted by at least two-thirds majority to override the veto, the bill would become law.
A spokesperson for House Speaker Nancy Pelosi (D-CA) stated: "Congress vigorously rejects any claim that the president has the authority to pocket-veto this legislation, and will treat any bill returned to the Congress as open to an override vote." A White House spokesperson has said: "A pocket veto, as you know, is essentially putting it in your pocket and not taking any action whatsoever. And when Congress — the House is out of session — in this case it’s our view that bill then would not become law."
Louis Fisher, a constitutional scholar at the Library of Congress indicated: "The administration would be on weak grounds in court because they would be insisting on what the Framers decidedly rejected: an absolute veto. By "absolute veto" Fisher was referring to the fact that a bill that has been pocket vetoed cannot be overridden. Instead, the bill must be reintroduced into both houses of Congress, and again passed by both houses, an effort which can be very difficult to achieve.
In the end, the House of Representatives did not attempt to override it. Instead, in January 2008, the House effectively killed H.R. 1585 by referring it to the Armed Services Committee. It then passed H.R. 4986, a bill nearly identical to H.R. 1585 but slightly modified to meet the President's objection, which subsequently became law.
This is not the first time that a President has attempted to pocket veto a bill despite the presence of agents to receive his veto message. Both George H. W. Bush and Bill Clinton made similar attempts.