Editing Declaration of war (section)

{{Use dmy dates|date=October 2023}}
{{Short description|Formal act by which one state announces war against another}}
{{Redirect|State of war}}
{{Other uses}}
[[File:Franklin Roosevelt signing declaration of war against Germany.jpg|thumb|upright=0.9|[[United States|US]] [[President of the United States|President]] [[Franklin D. Roosevelt]] signs a declaration of war against [[Nazi Germany]] on 11 December 1941.]]
A '''declaration of war''' is a formal act by which one [[state (polity)|state]] announces existing or impending [[war]] activity against another. The declaration is a performative [[speech act]] (or the public signing of a document) by an authorized party of a national government, in order to create a '''state of war''' between two or more [[Sovereign state|states]].

The legality of who is competent to declare war varies between nations and forms of government. In many nations, that power is given to the [[head of state]] or [[monarch|sovereign]]. In other cases, something short of a full declaration of war, such as a [[letter of marque]] or a [[covert operation]], may authorise war-like acts by [[privateer]]s or [[mercenary|mercenaries]]. The official international protocol for declaring war was defined in the [[Hague Conventions of 1899 and 1907|Hague Convention (III) of 1907 on the Opening of Hostilities]].

Since 1945, developments in international law such as the [[United Nations Charter]], which prohibits both the threat and the [[Use of force in international law|use of force]] in international conflicts, have made declarations of war largely obsolete in international relations,<ref name="HOL">{{cite web |url=https://publications.parliament.uk/pa/ld200506/ldselect/ldconst/236/236i.pdf |title=Waging war: Parliament's role and responsibility |date=27 July 2006 |publisher=[[House of Lords]] |access-date=21 April 2008 |quote=Developments in international law since 1945, notably the United Nations (UN) Charter, including its prohibition on the threat or use of force in international relations, may well have made the declaration of war redundant as a formal international legal instrument (unlawful recourse to force does not sit happily with an idea of legal equality).}}</ref> though such declarations may have relevance within the domestic law of the belligerents or of neutral nations. The UN Security Council, under powers granted in articles 24 and 25, and Chapter VII of the Charter, may authorize [[collective action]] to maintain or enforce international peace and security. Article 51 of the United Nations Charter also states that: "Nothing in the present Charter shall impair the inherent right to individual or collective self-defence if an armed attack occurs against a state."<ref name="UN_Charter">{{cite book |title=Charter of the United Nations |title-link=wikisource:Charter of the United Nations |at=art. 51}}</ref>

Declarations of war have been exceedingly rare since the end of World War II.<ref name=":0">{{Cite journal|last1=Irajpanah|first1=Katherine|last2=Schultz|first2=Kenneth A.|date=2021|title=Off the Menu: Post-1945 Norms and the End of War Declarations|url=https://doi.org/10.1080/09636412.2021.1979842|journal=Security Studies|volume=30|issue=4|pages=485–516|doi=10.1080/09636412.2021.1979842|s2cid=239546101|issn=0963-6412|url-access=subscription}}</ref><ref name=":1">{{Cite journal|last=Fazal|first=Tanisha M.|date=2012|title=Why States No Longer Declare War|url=https://doi.org/10.1080/09636412.2012.734227|journal=Security Studies|volume=21|issue=4|pages=557–593|doi=10.1080/09636412.2012.734227|s2cid=143983917|issn=0963-6412|url-access=subscription}}</ref> Scholars have debated the causes of the decline, with some arguing that states are trying to evade the restrictions of [[international humanitarian law]] (which governs conduct in war)<ref name=":1" /> while others argue that war declarations have come to be perceived as markers of aggression and maximalist aims.<ref name=":0" />