Article 15 of the European Convention on Human Rights allows States, in time of "war or other public emergency threatening the life of the nation," to take measures derogating from their obligations to protect human rights. This brief monograph by a member of the Registry of the European Court of Human Rights offers a personal view on the possibilities of derogation in practice. Its aim is to inform discussion on the relevance today of Article 15 as part of the Convention system. Its main focus is on armed conflict, both international and non-international, and on terrorism. It makes proposals to breathe new life into Article 15. Subject: Human Rights Law, European Law]