T his report presents information on the constitutional basis for vetoes, veto override procedure, and veto threats. It concludes with tables providing the counts of regular vetoes, pocket vetoes, and vetoes of appropriations acts. The President's veto authority is among the most significant tools in the executive branch's dealings with Congress. The U.S. Constitution outlines the veto authority in Article I, Section 7. Thirty-seven of 44 Presidents have used the veto. Presidents have vetoed 2,572 acts since 1789; of these, Congress has overridden 110 (4.3%). The U.S. Constitution (Article I, Section 7) provides that, for a bill to become law, it must be approved by both houses of Congress and presented to the President for approval and signature. Article I, Section 7 also provides the President with the power to veto, or "forbid," the bill from becoming law. The President may sign a bill into law within the 10-day period (excluding Sundays), let the bill become law without signature, or veto the bill. The Constitution states that when the President vetoes a bill, "he shall return it, with his Objections to that House in which it shall have originated." For example, if the President vetoes a bill that was introduced in the Senate, the bill will be returned first to the Senate where the possible override process would begin. This type of action is called a "regular" or "return" veto. If, on the other hand, Congress has adjourned within the 10-day period after presentation of the bill to the President (thereby preventing the return of the bill to Congress), the President may refuse to sign the bill, and the act does not become law—a practice called a "pocket" veto. If a bill is pocket vetoed while Congress is out of session, the only way for Congress to circumvent the pocket veto is to reintroduce the legislation as a new bill, pass it through both chambers, and present it to the President again for signature. On the other hand, Congress may override a regular veto without introducing new legislation through the process described in the U.S. Constitution. According to Article 1, Section 7 of the Constitution, when the President chooses not to sign a bill and instead returns it to the chamber from where it originated, the chamber enters the message of the President detailing the reasons for his or her refused approval into its Journal and then proceeds "to reconsider" the bill. Because the Constitution does not state exactly how Congress should reconsider a vetoed bill, House and Senate procedures govern the specific treatment of acts returned by the President. Passage by a two-thirds margin in both chambers is required to override a veto before the end of the Congress in which the veto is received. If a two-thirds vote is successful in the originating chamber, that chamber informs the other of its decision to override the veto by message. Neither chamber is under any constitutional, legal, or procedural obligation to schedule an override vote. It is not unusual for Congress to make no effort to override the veto if congressional leaders do not believe they have sufficient votes. A veto threat can also prove to be an effective tool for the President, sometimes forcing Congress to modify legislation before presenting the bill to the President. In addition to public addresses concerning legislation, the President has the ability to issue Statements of Administration Policy (SAPs) to express the Administration's view on a bill. SAPs are a written form of communication between the Administration and Congress and are typically issued shortly before floor action on the bill. The Office of Management and Budget coordinates the creation of SAPs on behalf of the Executive Office of the President. SAPs communicate varying levels of Administration support or opposition to a bill. Importantly, SAPs are generally the first formal indicator of the Administration's intent to veto a bill. SAPs containing veto threats contain language indicating either the President's intent to veto, the President being advised to veto by agencies, or the President being advised to veto by the Administration's senior advisors. SAPs are transmitted by the White House to Congress; they are also available on the White House website. Table 1 shows that 37 of 44 Presidents have exercised their veto authority on a total of 2,572 occasions since 1789. Of that number, 1,506 (58.6%) were regular vetoes—that is, the rejected legislation was returned to the congressional chamber of origin, while it was in session, with a presidential message of explanation—and 1,066 (41.5%) were pocket vetoes, or rejected while Congress was adjourned. Congress has overridden 110 (7.3%) of the 1,506 regular vetoes. This percentage is skewed downward by the large number of vetoes prior to the 87 th Congress (which began in 1961). If one counts only the regular vetoes since 1961 (the beginning of the Kennedy Administration), one finds 241 vetoes and 37 overridden (15.4%). George W. Bush (2001-2009) was the first President since John Quincy Adams (1825-1829) to serve a full four-year term without using his veto. No President since Thomas Jefferson (1801-1809) has served two full terms without vetoing a bill, as President Bush used his veto in July 2006. President Barack H. Obama has vetoed 10 bills since taking office in 2009. The three most recent vetoes, which all took place during the second session of the 114 th Congress, were of H.R. 3762 , Restoring Americans' Healthcare Freedom Reconciliation Act of 2015; S.J.Res. 22 , A joint resolution providing for congressional disapproval under Chapter 8 of title 5, United States Code, of the rule submitted by the Corps of Engineers and the Environmental Protection Agency relating to the definition of "waters of the United States" under the Federal Water Pollution Control Act; and H.J.Res. 88 , Disapproving the rule submitted by the Department of Labor relating to the definition of the term "Fiduciary." A veto of an appropriations bill can result in a funding gap, which may lead to the closure of federal agencies, the furlough of federal employees, and the interruption of federal programs and services. Despite these potential outcomes, Presidents have vetoed 83 appropriations bills since 1789; more than half of these vetoes have occurred since 1968. For example, Presidents Carter, Reagan, George H. W. Bush, and Clinton were presented with a total of 387 appropriations acts and vetoed 30 of them (7.8%). President Barack H. Obama has vetoed one appropriations bill. Congressional overrides of vetoes of appropriations are not unusual; 12 of the 83 vetoes (14.5%) have been overridden (see Table 2 ).