WHAT CONSTITUTES RELEVANT STATE PRACTICE?

In keeping with the analysis of the proper role of state practice developed in Chapter 8 – which is to serve as evidence of opinio juris – it is desirable to adopt a broad definition of “practice.” Virtually any kind of conduct by any agent of a state or international organization has a potential bearing on opinio juris. The weight of a particular kind of conduct as evidence of opinio juris will vary based on the principles discussed previously.

A number of theorists – even those who view state practice as an independent requirement in accordance with the traditional definition of customary law – adopt this wide perspective. For example, Sinclair states, “The better view would appear to be that State practice covers any act or statement made by or on behalf of a State from which its view can be inferred about the existence or content of a rule of international law.” Akehurst asserts, “State practice covers any act or statement by a State from which views can be inferred about international law.” The Restatement (Third) of the Foreign Relations Law of the United States adopts a similarly broad view of state practice to include “diplomatic acts and instructions as well as public measures and other governmental acts and official statements of policy, whether they are unilateral or undertaken in cooperation with other states, for example in organizations such as the Organization for Economic Cooperation and Development (OECD).”