ABSTRACT
The Monroe Doctrine illustrated how the interpretation of unilateral acts changed in between the early nineteenth century and the middle of the twentieth century. This chapter traces the history of an obligation erga omnes. It highlights a core problem with asserting that a unilateral act was an obligation erga omnes. The chapter demonstrates that formulating unilateral acts as obligation erga omnes was an unsatisfactory solution to the problems presented by the earlier attempt to legalize unilateral acts through consent. It outlines the International Court of Justice (ICJ) displayed the mid-twentieth century pragmatism. The Nuclear Tests Cases also established a new doctrinal basis for unilateral acts. The Court now tied the legal effect of unilateral acts to the principle of good faith, moving away from consent. The decision stated: One of the basic principles governing the creation and performance of legal obligations, whatever their source, is the principle of good faith.
