The primary objective of this research is to suggest an effective legal regime to control marine pollution which may result from development of petroleum resources in the United Kingdom and Norwegian sectors of the North Sea. The conclusions upon which the model legal regime are based, as well as the discussion of relevant issues, will be useful to consider in evaluating pollution control from petroleum development in other offshore areas. The research concerns three major areas: 1) offshore petroleum development activities which pose a threat of environmental injury, 2) the present international and national law regulating these activities, and 3) a suggested model legal regime to provide optimum environmental protection. The analysis of the causes and effects of marine pollution is primarilly concerned with sea-based sources of environmental damage; it considers vessels, petroleum transfer and refining, and offshore petroleum development. The role of land-based marine pollution sources is also discussed in connection with the capability of the North Sea to assimilate all materials which may enter it as a result of human activity. The most recent scientific findings concerning effects of petroleum and other substances on the marine environment are summarised. It is concluded that: 1) the most likely cause of short-term environmental injury is a massive oil spill from a tanker, 2) chronic discharges of effluents from vessels and installations may also result in environmental damage, and 3) inability to definitively predict the long-term effects of substances discharged into the marine environment may require enactment of protective legislation prior to complete understanding of possible injury. The analysis of the present legal regime involves a critical examination of existing law and an attempt to determine how effective is the protection afforded. This appraisal considers the international law regulating pollution from seabed operations, the international law of responsibility for marine pollution, industry compensation schemes, the United Kingdom law regulating pollution from seabed operations, the United Kingdom law of liability for marine pollution, the Norwegian law regulating pollution from seabed operations, and the Norwegian law of liability for marine pollution. Attention is drawn to the emerging law of the sea where relevant, for example, the activities of the third United Nations Conference on the Law of the Sea, unilateral acts of States, and actions of international organizations. It is concluded that: 1) the present legal regime is comprised of independently developed components which remain uncoordinated, and 2) legal protection of the environment is determined by a complex of societal values, not only by scientifically determined need. The suggested model legal regime attempts to coordinate laws and reconcile values to the extent realistically possible. Coordination of national and international law concentrates on establishing a system of uniform standards and enforcement for the United Kingdom and Norwegian areas. The nature and scope of this system are determined by the extent to which disparate societal values can be reconciled. An interdisciplinary approach is employed to weigh carefully multiple factors - economic, technological, sociological and political - in order to provide a solid foundation upon which to base the suggested model legal regime.