CHICAGO JoHN M. OLIN LAW EcoNoMIcs WORKINg PAPer no. 63 (2D SERIES) A Theory of Customary International Law Jackl. goldsmith and eric A. Posner THE LAW SCHOOL THE UNIVERSITY OF CHICAGO This paper can be downloaded without char The Chicago Working Paper Series Index http://www.lawuchicago.edu/publicatIons/working/index.html The Social Science Research Network Electronic Paper Collection http://papers.ssrn.com/paper.taf?abstract_id=145972This paper can be downloaded without charge at: The Chicago Working Paper Series Index: http://www.law.uchicago.edu/Publications/Working/index.html The Social Science Research Network Electronic Paper Collection: http://papers.ssrn.com/paper.taf?abstract_id=145972 CHICAGO JOHN M. OLIN LAW & ECONOMICS WORKING PAPER NO. 63 (2D SERIES) A Theory of Customary International Law Jack L. Goldsmith and Eric A. Posner THE LAW SCHOOL THE UNIVERSITY OF CHICAGO