Published online by Cambridge University Press: 11 April 2007
In this article I examine how a weak international law can be created despite the presence of a strong norm, and I use weak law to probe the relationship between social and legal norms. International law dealing with mercenaries is notoriously flawed. These flaws have been attributed to the idea that state interest (or lack of interest) led to the development of intentionally weak law. In fact, ineffective anti-mercenary law is the result of the influence of norms. A strong norm against mercenary use has led states to devise a definition that indicated what they found problematic about mercenaries, and differentiated mercenaries from other actors. This definition followed the anti-mercenary norm but created a number of loopholes, which were made worse by the fact that commitment to the norm was so strong that states were unable to make adjustments necessary to create more effective law. The development of the law against mercenaries was further undermined by the pressures of a competing norm. During the 1980s, creation of a UN Convention to deal with mercenaries was stymied by the fact that many states were seeking to protect the norm of state responsibility, and the conflict between this norm and the anti-mercenary norm delayed the Convention to such a degree it was superseded by events. Weak anti-mercenary law, created in the presence of a strong anti-mercenary norm, can demonstrate four things about the relationship between social and legal norms: that states advocate the creation of law because of what it is rather than what it does; that legal institutionalization is not necessarily good for the further development of a norm; that strong commitment to a norm can lead to the creation of weak law; and that social and legal norms might not differ because the latter is more effective.The author would like to thank Audrey Kurth Cronin, Guy Goodwin-Gill, Henry Shue, Adam Roberts, Henry Shue, Christine Whelan, Dominik Zaum, and the two anonymous referees, for their comments. Helpful comments were made by Joanna Harrington and Neil MacFarlane on an earlier version of this piece.