Public international law, through its rules regulating the dealings between independent nations, purports to impose limits on the actions of all governments, including those of the United States. In this context American lawyers interested in foreign relations may reasonably wonder whether American courts would enforce rules of public international law purporting to bind the United States against the United States government, particularly the executive branch. A fair number of Supreme Court cases have dealt with the enforce ability of treaties in American courts.' Treaties, however, are only one source of international law. The other important source, customary international law, is neither expressly mentioned in the Constitution nor much discussed in Supreme Court cases. Customary international law also differs in important respects from treaties. Treaties are by necessity purely consensual arrangements between the parties. Rules of customary law, as the definition implies, are matters of general practice that can come into existence if a practice can fairly be labelled "general." Thus, a state that did not actively participate in the practice that culminated in the creation of a rule could find itself bound by the rule anyway, at least if that state did not actively dissent during the period of the rule's gestation.
Recently, the question whether the federal courts have the authority to compel the President to adhere to rules of customary international law has drawn comment from writers interested in the subject. Some have taken the position that the courts in fact possess such authority, at least when Congress has not by statute established for the United States a rule different from that which international law would apply to the issue in question.' According to these writers, one withstanding to complain of a contemplated presidential action that would violate customary international law should be able to obtain from a federal court an injunction forbidding the action. For example, some have suggested that the federal courts could, on the basis of customary inter-national law, forbid the Executive to mine Nicaragua's harbors or control the Executive's treatment of undocumented aliens...
This Article argues that the President is not bound by international law. Of course, when statutes or constitutional provisions duplicate rules of international law, the President would act unlawfully if he violated these statutes or constitutional provisions. Whether the act was also a violation of international law would be irrelevant.
Arthur M. Weisburd,
The Executive Branch and International Law,
41 Vanderbilt Law Review
Available at: https://scholarship.law.vanderbilt.edu/vlr/vol41/iss6/3