The Role of Experts in Proving International Human Rights Law in Domestic Courts

Neither the Federal rules of Civil Procedure not the Federal Rules of Evidence make any overt reference to the method of proving customary international law in United States courts. Nonetheless, the content and applicability of customary international law is usually proven by expert testimony in United States courts. International legal experts serve both as advocates for particular interpretations of international law and as assistants to the court in understanding the international legal system. Neither a single authoritative text nor a single authoritative decisions maker exists with respect to the content of customary international law. All international law is, in effect, human rights law since only human beings can make or benefit from legal rules. Thus, expert witnesses in international human rights cases perform no differently than do experts with respect to general international law. The sovereign state is merely a conduit through which human beings act and communicate. The legal expert determines and describes the expectations of pattern and uniformity that are evidenced by those communications. Thus, the expert testifies based on empirical and theoretical knowledge of the international legal system. In this sense, the international legal expert functions much like an expert in sociology or anthropology. The expert testimony from the Cuban Mariels cases illustrates that international legal experts often testify on related domestic law issues as well.