Legitimacy in the use of force: Opinio or Juris?

John Hardy

Research output: Chapter in Book/Report/Conference proceedingConference proceeding contributionpeer-review


Debates about the recourse to force in international politics often conflate legality and legitimacy. The legitimate use of force is often associated with legality and illegitimacy is generally associated with illegality. But the relationship between the two concepts is not linear and recent examples such as the proposed Syrian intervention and the NATO air campaign in Kosovo show that legitimacy and legality are not necessarily cognates. This paper separates opinion from international law and argues that many commentators have inflated the role of law in determining the legitimacy of actual or proposed uses of armed force. It argues that the principle purpose of international security law is to codify norms of behaviour which states find acceptable in order to facilitate cooperation and collective action. Because laws exist to reduce risks and transaction costs between international actors, they are representations of standards which already exist and are not in themselves the final arbiter of legitimacy. Rather, legitimacy is determined by a more ethereal and dynamic combination of norms which determine what conditions actors collectively feel constitute ‘the right thing to do.’ This explains widespread advocacy for the use of force for humanitarian purposes without legal authorization under certain circumstances.
Original languageEnglish
Title of host publicationProceedings of the Sixth Oceanic Conference on International Studies
Place of PublicationMelbourne
PublisherUniversity of Melbourne
Number of pages17
Publication statusPublished - 2014
Externally publishedYes
EventOceanic Conference on International Studies (6th : 2014) - Melbourne
Duration: 9 Jul 201411 Jul 2014


ConferenceOceanic Conference on International Studies (6th : 2014)


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