A declaration of war is a formal declaration issued by a national government indicating that a state of war exists between that nation and another. A document by the Federation of American Scientists gives an extensive listing and summary of statutes which are automatically engaged upon the United States declaring war.

Article One of the Constitution of the United States establishes the legislative branch of the federal government, the United States Congress. Under Article One, Congress is a bicameral legislature consisting of the House of Representatives and the Senate. Article One grants Congress various enumerated powers and the ability to pass laws "necessary and proper" to carry out those powers. Article One also establishes the procedures for passing a bill and places various limits on the powers of Congress and the states from abusing their powers.