Customary Law, General Principles, Unilateral Acts

  • Malgosia FitzmauriceEmail author


This contribution deals in particular with an undisputed and fundamental contribution of Nicaragua cases to the development of customary international law. The question of customary international law in the Nicaragua cases has become a central issue in the whole debate on this source of international law. The approach of the Court to the two-element structure of customary international law, has been a source of an invigorating scholarly discussion and speculation. To some extent the author of this contribution also engages into the debate how customary international law has developed further through judicial practice, in particular that of the International Court of Justice, not lacking in controversy. This contribution deals with general principles of law, focusing on the principle of res judicata. Finally, it deals with unilateral acts, focusing on the legal character of optional declaration within the system of compulsory jurisdiction of the International Court of Justice, reliance on which in the Nicaragua v. United States case was met with a very robust debate.


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© Springer International Publishing AG 2018

Authors and Affiliations

  1. 1.Department of LawQueen Mary, University of LondonLondonUK

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