The Use of Force Against Terrorists

44 Pages Posted: 12 Jun 2009 Last revised: 10 Mar 2011

See all articles by Christian J. Tams

Christian J. Tams

University of Glasgow, School of Law

Date Written: June 9, 2009


There is much debate whether States are entitled to use force against terrorists based in another country. The relevant provisions of the UN Charter do not provide a conclusive answer, but have to be interpreted. The present article suggests that in the course of the last two decades, the Charter regime has been re-adjusted, so to permit forcible responses against terrorism under more lenient conditions. In order to illustrate developments, it juxtaposes the international law as of 1989 to the present state of the law. It argues that the restrictive approach to anti-terrorist force obtaining twenty years ago has come under strain. As far as collective responses are concerned, it is no longer disputed that the Security Council could authorise the use of force against terrorists; however, it has so far refrained from doing so. More controversially, the international community, during the last two decades, has increasingly recognised a right of States to use unilateral force against terrorists. This new practice is justified under an expanded doctrine of self-defence. It can be explained as part of a strong international policy against terrorism and is part of an overall tendency to view exceptions to the ban on force more favourably than twenty years ago. Conversely, it has led to a normative drift affecting key limitations of the traditional doctrine of self-defence, and increases the risk of abuse.

Keywords: terrorism, international terrorism, use of force, terrorists, self-defence, 9/11, non-State actors, attribution, International Court of Justice, Nicaragua, Israeli Wall

Suggested Citation

Tams, Christian J., The Use of Force Against Terrorists (June 9, 2009). Available at SSRN: or

Christian J. Tams (Contact Author)

University of Glasgow, School of Law ( email )

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