Nineteen ninety-two provided several painful reminders of the inherent hazards of oil tankers plying the high seas loaded with millions of gallons of crude oil. Within the space of a few days we witnessed a succession of catastrophic accidents: the foundering of the Greek AEGEAN SEA off the North-West coast of Spain, the breaking-up of the Liberian BRAER off the Shetland Islands, and the burning of the Danish-owned MAERSK NAVIGATOR near the entrance to the Indian Ocean's Malaccan Strait. Any one of these accidents could have been worse than the EXXON VALDEZ spill in Alaska in 1989, when 11 million gallons of crude oil leaked into Prince William Sound. This once again demonstrated the imperative need for an improved regime for the prevention of this kind of accident. The 1982 United Nations Convention on the Law of the Sea, which had been ratified by 54 states by the end of 1992, consolidates a number of novel provisions, one of which is port state enforcement for violations outside a state's jurisdiction. Port state control, as such, is a very old concept. It is based on the rule of international law, according to which a state exercises full jurisdictional powers within its internal waters and has the right to deny access to such waters. The 1982 Convention expands this jurisdiction and provides the port state with enforcement powers with respect to violations outside its national jurisdiction. Special emphasis is paid to the evolution of the port state enforcement regime; its formulation in the 1982 UN Convention on the Law of the Sea; advantages and disadvantages and finally the implementation of the enforcement provisions of relevant maritime conventions. This book also analyses flag state jurisdiction and the repercussions of the adoption of the 1986 Convention for Registration of Ships. Special emphasis is given to a regional European agreement, the 1982 Paris Memorandum of Understanding, which attempts to strengthen the implementation of the existing international legal standards that could serve as a model for a future port state regime.