Three recent International Court of Justice decisions - Oil Platforms, Avena and Wall in the Occupied Palestinian Territory - highlight the uncertain status of the margin of appreciation doctrine in the Court's jurisprudence. The purpose of this article is to evaluate, in the light of contemporary practice of other courts, the current status under international law of the margin of appreciation doctrine, which encourages international courts to exercise restraint and flexibility when reviewing the decisions of national authorities, and to offer preliminary guidelines for future application. The article also discusses a variety of policy arguments concerning the legitimacy and effectiveness of international courts, which can be raised in support of the development of a general margin of appreciation doctrine with relation to some categories of international law norms governing state conduct, and it examines potential criticism. Eventually, it argues that the same considerations which have led to the creation of 'margin of appreciation type' doctrines in the domestic law of many states and in the context of specific international regimes (for instance, the European Convention on Human Rights) also support the introduction of the doctrine into general international law. The position of the ICJ towards the application of the doctrine therefore merits reconsideration.