Declaration of war by the United States

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. The document Declarations of War and Authorizations for the Use of Military Force: Historical Background and Legal Implications gives an extensive listing and summary of statutes which are automatically engaged upon the US declaring war.

For the United States, Article One, Section Eight of the Constitution says "Congress shall have power to ... declare War". However, that passage provides no specific format for what form legislation must have in order to be considered a "declaration of war" nor does the Constitution itself use this term. In the courts, the United States Court of Appeals for the First Circuit, in Doe v. Bush, said: "[T]he text of the October Resolution itself spells out justifications for a war and frames itself as an 'authorization' of such a war." in effect saying an authorization suffices for declaration and what some may view as a formal Congressional "Declaration of War" was not required by the Constitution.

This article will use the term "formal declaration of war" to mean Congressional legislation that uses the phrase "declaration of war" in the title. Elsewhere, this article will use the terms "authorized by Congress", "funded by Congress" or "undeclared war" to describe other such conflicts.

The United States has formally declared war against foreign nations five separate times, each upon prior request by the President of the United States. Four of those five declarations came after hostilities had begun. James Madison reported that in the Federal Convention of 1787, the phrase "make war" was changed to "declare war" in order to leave to the Executive the power to repel sudden attacks but not to commence war without the explicit approval of Congress. Debate continues as to the legal extent of the President's authority in this regard. Public opposition to American involvement in foreign wars, particularly during the 1930s, was expressed as support for a Constitutional Amendment that would require a national referendum on a declaration of war. Several Constitutional Amendments, such as the Ludlow Amendment, have been proposed that would require a national referendum on a declaration of war.

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