A historical analysis of state responsibility shows that this body of law developed from an implicit doctrine into a separate topic of international law over the centuries. The traditional law of state responsibility was confined to injuries to aliens, largely due to the widespread resort to international arbitration in the second half of the nineteenth century. Following scholarly interest in responsibility, codification initiatives mushroomed with the domestic analogy playing a varying role. Progress in codification was made only in the 1960s with the abandonment of the controversial traditional law of state responsibility for the benefit of generalized and secondary rules on state responsibility. State responsibility now became important for the role it played with respect to legality and rule of international law; yet, its foundation was based on bilateral state relations and remedying of concrete wrongs. As a consequence, the law of state responsibility as codified in the 2001 Articles on State Responsibility remains infused with tensions and dilemmas, in addition to which the legal form and effect of the Articles have remained under debate.