The principle of non-refoulement found in the UN Convention on the Status of Refugees has been widely regarded as the core element of the international refugee protection regime. However, in the recent era of restrictive external migration controls, its significance and ambit diminished to the extent that states began to regard it as a general moral principle that imposed only narrowly defined legal constraints. In particular, interception or interdiction of refugees on the high seas came to be regarded as activities falling outside the legal ambit of the non-refoulement obligation. However, in Europe, this has begun to change. The non-refoulement obligation found in Article 3 of the European Convention on Human Rights (ECHR) has been recognized as a legal constraint on state sovereignty in relation to migration controls on the high seas. This article scrutinizes how the developing concept of jurisdiction in human rights law, particularly as found in the ECHR, has expanded the scope of application of the principle of non-refoulement, and presents some important implications. The concept of state sovereignty has begun to undergo a paradigm shift that places extraterritorial human rights concerns relating to external migration controls squarely within a legal rather than merely a moral framework.