The author starts by observing that discussions about the foundations and the limits of the powers of international courts, including those of the European Court of Human Rights (hereafter ECtHR), turn around the aims of achieving legal certainty, ensuring legitimacy and justice, and avoiding conflicting obligations which may emanate from different regimes of international law. The chapter reflects on these aims from the perspective of consent as the common basis of the main sources of international law, as listed in Article 38 of the Statute of the International Court of Justice. Proceeding from the case law of the ECtHR, the chapter explores how the recent work of the International Law Commission conceives the role of consent in respect of the main sources of international law, and whether the jurisprudence of the ECtHR remains within the framework of general international law so enunciated.