what is a pocket veto?

A pocket veto is a presidential veto, but of a particular type. The U.S. Constitution limits the President's period for decision on whether to sign or veto any legislation to ten days (not including Sundays) while the United States Congress is in session. The Constitution provides for two types of vetoes: a regular or return veto, when the president sends a bill, along with his objections, back to the house of Congress in which the bill originated. Congress can override the veto by 2/3 vote of both houses, whereupon the bill becomes law. A pocket veto only comes into play when Congress by its adjournment prevents return of the bill. Thus, a pocket veto can only occur under two circumstances: a) if Congress is adjourned, and b) if bill return to Congress is not possible (bill return is possible when Congress has adjourned, but has designated an agent to receive veto messages and other communications, an action Congresses have taken routinely for decades). If, under these circumstances, the president withholds his signature, the bill dies instead of becoming law. That is the pocket veto. (If the president neither signs nor vetoes a bill when Congress is in session, the bill becomes law without his signature after 10 days.) Article 1, Section 7 of the U.S. Constitution states:

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.