Formation of Rules of Customary Int'l Law

Committee Mandate

The Committee has undertaken a comprehensive study of the customary law status of human rights, building on the study that Prof. Richard Lillich led at the Buenos Aires Conference of the International Law Association in 1994 on the status of the Universal Declaration of Human Rights in national and international law, and also on the 2000 study of the International Law Association, published at its London Conference, entitled “Statement of Principles Applicable to the Formation of General Customary International Law”.

The study will also draw upon our Committee’s own prior work on the role of national court decisions as state practice and on the role of state practice in the formation of customary and jus cogens norms of international law (both available at, as well as on new approaches, such as those developed in recent books. These include Brian D. Lepard, “Customary International Law: A New Theory with Practical Applications,” published by Cambridge University Press in 2010; Andrew T. Guzman, “How International Law Works: A Rational Choice Theory,” published by Oxford University Press in 2008; and Amanda Perreau-Saussine and James B. Murphy, eds., “The Nature of Customary Law: Legal, Historical and Philosophical Perspectives,” published by Cambridge University Press in 2007. Also influential is likely to be the ICRC’s multi-volume study on “Customary International Humanitarian Law.”

Committee Leaders


Prof. Brian Lepard

19 members

Committee Members