The contingency planning arrangements for offshore oil and gas accidents in the European Union constitute probably the archetypal case-book study. In addition to the traditional offshore fields around Norway and the United Kingdom, more and more offshore installations are now situated in the Mediterranean waters. The transboundary impact of an accident in one of the most heavily used coastal areas on the planet, where other uses and users of the sea aggravate geographic proximity, underlines the severity of the risk. Directive 2013/30/EU on safety of offshore oil and gas operation is the EU response to such concerns, upon a comprehensive review of the existing international, European and domestic regulatory framework, involving both the competent national authorities and the industry. This chapter presents and critically reviews the international context, the specific content and the expected impact of the resulting legislative exercise – which remains uncontested by the ravages of real life. The Arctic is of special concern with respect to oil spills due to their potential environmental consequences and the region’s specific challenges for effective oil spill response (OSR). An Arctic spill of significant magnitude will require international cooperation to be handled effectively. We therefore ask whether there exists an adequate legal and institutional framework for cooperation on OSR, focusing on the pan-Arctic MOSPA Agreement of 2013 and the bilateral Norwegian-Russian OSR Agreement of 1994. We outline the substantive rights and duties established by the agreements, their operative arrangements and decision-making procedures. Further, we present experiences of the agreements in action through exercises. The study concludes that the agreements provide a sufficient legal basis for OSR cooperation. However, they both have a low level of institutionalization and decision-making capacity. Further, uncertainties remain as to how they would perform during an actual oil-spill requiring a joint operation. Recognition that oil spill response and planning are complicated and may not abide national boundaries has led to a series of regionally focused arrangements. The present chapter examines the regulatory situation in the North American Arctic, including the United States, Canada, and Greenland. It does so, first, by critically reviewing national oil spill prevention and response, and, second, by examining international cooperation and coordination among the three North American Arctic states. It traces each country’s different legal and regulatory regime to deal with the myriad challenges of responding to spills in the Arctic and identifies several important steps that could be taken to improve contingency planning and preparedness. It concludes that all three North American Arctic nations’ approaches, moreover, would benefit from increased integration. The consequences of an incident on the seabed of one State are often likely to affect also the waters and the coastline of neighboring States. A State that has enacted strict measures to prevent polluting incidents within its own jurisdiction could be affected by pollution due to a more permissive regime applied by a neighboring State. This is why there is a need for international agreements to prevent oil spills and to coordinate the response, when they occur. This chapter focuses on international cooperation for the prevention of, and response to, oil spills, with emphasis on the situation at the regional seas level. Special consideration is given to the Protocol concerning Pollution Resulting from Exploration and Exploitation of the Continental Shelf, the Seabed and its Subsoil (Madrid, 1994), adopted within the framework of the Convention for the Protection of the Marine Environment and the Coastal Region of the Mediterranean (Barcelona, 1976).