The United States Congress overrides President Richard M. Nixon's veto of the War Powers Resolution, which limits presidential power to wage war without congressional approval.

The War Powers Resolution (also known as the War Powers Resolution of 1973 or the War Powers Act) (50 U.S.C. ch. 33) is a federal law intended to check the U.S. president's power to commit the United States to an armed conflict without the consent of the U.S. Congress. The resolution was adopted in the form of a United States congressional joint resolution. It provides that the president can send the U.S. Armed Forces into action abroad only by declaration of war by Congress, "statutory authorization", or in case of "a national emergency created by attack upon the United States, its territories or possessions, or its armed forces".

The War Powers Resolution requires the president to notify Congress within 48 hours of committing armed forces to military action and forbids armed forces from remaining for more than 60 days, with a further 30-day withdrawal period, without congressional authorization for use of military force (AUMF) or a declaration of war by the United States. The resolution was passed by two-thirds each of the House and Senate, overriding the veto of President Richard Nixon.

It has been alleged that the War Powers Resolution has been violated in the past for example, by President Bill Clinton in 1999, during NATO bombing of Yugoslavia. Congress has disapproved all such incidents, but none has resulted in any successful legal actions being taken against the president for alleged violations.

The United States Congress is the legislature of the federal government of the United States. It is bicameral, being composed of a lower body, the House of Representatives, and an upper body, the Senate. The Congress meets in the United States Capitol in Washington, D.C. Both senators and representatives are chosen through direct election, though vacancies in the Senate may be filled by a governor's appointment. Congress has 535 voting members: 100 senators and 435 representatives. The vice president of the United States has a vote in the Senate only when senators are evenly divided. The House of Representatives has six non-voting members.The sitting of a Congress is for a two-year term, at present, beginning every other January. Elections are held every even-numbered year on Election Day. The members of the House of Representatives are elected for the two-year term of a Congress. The Reapportionment Act of 1929 establishes that they be elected in single-member constituencies or districts by first-past-the-post and that Congressional districts be apportioned to states by population every ten years using the United States Census results, provided that each state has at least one Congressional representative. Each senator is elected at-large in their state for a six-year term, with terms staggered, so every two years approximately one-third of the Senate is up for election. Each state, regardless of population or size, has two senators, so currently, there are 100 senators for the 50 states.

Article One of the United States Constitution requires that members of Congress must be at least 25 years old (House) or at least 30 years old (Senate), have been a citizen of the United States for seven (House) or nine (Senate) years, and be an inhabitant of the state which they represent. Members in both chambers may stand for re-election an unlimited number of times.

The Congress was created by the Constitution of the United States and first met in 1789, replacing in its legislative function the Congress of the Confederation. Although not legally mandated, in practice since the 19th century, Congress members are typically affiliated with one of the two major parties, the Democratic Party or the Republican Party, and only rarely with a third party or independents affiliated with no party. In the case of the latter, the lack of affiliation with a political party does not mean that such members are unable to caucus with members of the political parties. Members can also switch parties at any time, although this is quite uncommon.