Abstract
Due diligence—the notion that international law includes a duty to cease and remedy damage that emanates from a State’s territory—has been proposed as an international legal measure to temper destabilizing effects of harm from cyber infrastructure. Yet the extent to which States, particularly the United States, accept due diligence as either a principle of general international law or as a rule of conduct applicable to the context of cyberspace is not clear. This Article examines past and present U.S. experience with due diligence, both as a principle and rule of conduct in general international law. In light of U.S. foreign relations history, a trend toward acceptance among allies and partners, and clear utility to State relations in cyberspace, we argue for renewed acceptance by the United States of the general principle of due diligence and its specific application to cyber operations.