The MARPOL (Marine Pollution) international convention forms the legal basis for the prevention of marine pollution by waste material from ships. In two reports and six annexes the 1973 agreement regulates what kind of ship refuse may be disposed of in which marine zones. In certain special areas, such as the North Sea, the Baltic and the Mediterranean, disposing of any kind of refuse into the sea – apart from waste food – is banned.
Annex V, which came into force in 1988, regulates how to deal with plastic garbage. In this category there is an absolute ban on disposal in all zones. Violations are punishable by fines of up to 50'000 euro. As monitoring ships on the open sea is relatively difficult, the same annex stipulates that a garbage diary should be kept. This enables a regulated way of handling garbage to be guaranteed.

Regional Seas Programme
The Regional Seas Programme of the United Nations (UNEP) dates back to 1974. The goal of this international program is to motivate neighboring countries to make a joint effort to protect divided areas of sea. Up to the present 18 regional programs have been developed. As most of the regional programs have their own administration, the UNEP is responsible mainly for overall coordination and for advice on how to implement the strategies in national and international legislation.The regional agreements encourage international collaboration and offer an opportunity to adapt protection programs to suit the situation of the particular maritime region. The theme of plastic pollution tends to be treated marginally in the European programs.

In 1975 the Mediterranean Sea was the first marine region with an action plan (Mediterranean Action Plan). A year later the agreement on protecting the Mediterranean from pollution was signed in Barcelona. Today it has 22 members. The protocols that define the concrete implementation deal with the following points: avoiding pollution through waste from ships, aircraft and from the land, establishing protected areas, collaboration in combating pollution caused by oil and pollutants in situations of emergencies, measures against excessive use of the sea, and joint coastal zone management. Current themes are the conservation of coastal zones and the encouragement of biodiversity.