The monograph tackles the issue of the current role of the coastal State in international marine environmental law with particular regard to the prevention of - and response to - vessel-source pollution. In Chapter I a critical examination is carried out of the international legal framework governing vessel-source pollution, its evolution, the interaction of the various sources of law involved and the role played by the major subjects involved, namely, the flag State, the coastal State and the port State. The necessary theoretical basis for the subsequent legal analysis are also provided, by way of a definition of the main concepts used throughout the work (ship, pollution, coastal State, etc.). Chapter II and Chapter III, respectively, deal with the prescriptive and the enforcement powers that may be exercised by coastal States. Unlike in other academic work devoted to the subject, the decision has been made by the author to opt for an approach based on the range of powers that may be used by the coastal State rather than on the different geographical areas under consideration. Such geographical areas (and their position under current international law with regard to ship-source pollution) are indeed duly taken into consideration, but within each thematic chapter and in the context of the either prescriptive or enforcement action that a coastal State may decide to conduct on a case-by-case basis. Specific attention, in this respect, is paid, in both Chapters II and III, to the interaction of the rules embodied in the 1982 UN Convention on the Law of the Sea with those provided for by so-called "technical" instruments adopted under the auspices of the International Maritime Organization (IMO) such as the 1973/1978 "Marpol" Convention and the 1974 "Solas" Convention. Chapter IV, finally, focuses on the ever increasing role of the European Community and European Union. A detailed description of the evolution of the European legislation in the field is provided, with a series of critical comments on issues such as the relationship between international and European law, the position of the European Community and European Union within the IMO, the overlap of (and possible conflicts between) European environmental and transport policies, the possibility for the European legislator to apply criminal sanctions to violators and the prospects for further evolution of this sector of European law.