This mograph analyses the questions raised by the legal effects of peremptory rms of international law (jus cogens). A comprehensive study of this problem has been lacking so far in international legal doctrine. Peremptory rms, although often criticised and even more often approached with sceptical nihilism, nevertheless attract growing doctrinal and practical attention and have increasing importance in determining the permissible limits on the action of State and n-State actors in different areas. In view of this overriding impact on what might otherwise be instances of the law-making process, peremptory rms concern a constitutional aspect of international law. Peremptory rms are n-derogable rms, and the concept of derogation is among the key concepts analysed here. Derogation from peremptory rms can be attempted in a wide variety of situations, but if peremptory rms are to operate as rms and t merely as aspirations they must generate consequences that are also peremptory. This effects-oriented character of peremptory rms is examined in a variety of fields. Despite the growing relevance of peremptory rms in practice, doctrine has failed to treat the issue comprehensively and has often been limited to examining specific aspects of the problem, such as the impact of peremptory rms in the law of treaties. This fresh effort to examine and explain the phemen of peremptory rms in key areas fills an important doctrinal gap through presenting in a systematic way the effects of peremptory rms and reappraising the significance of such effects, bearing in mind their overall nature. It also demonstrates that the hierarchical superiority of peremptory rms is t limited to the sphere of primary legal relations but becomes most crucially relevant after a specific peremptory rm is breached. A rm's peremptory character is relevant t only for its substance but also for its consequences; peremptoriness consists primarily in the capacity to impact through its effects upon conflicting acts, situations and agreements.
Alexander Orekhelashvili has previously lectured at the University of London, Queen Mary and Westfield College in Public International Law, and the Law of Armed Conflict. He has been a visiting research fellow at the Max-Plank Institute of International and Comparative Law, and a tutor in International Law at Jesus College, Cambridge. He is widely published both in Russia and in the West in the fields of Public International Law, Human Rights, Conflict and Security Law, and Comparative Law.