ABSTRACT ZHAFIRAH ULFAH, 2020 Nellyana Roesa, S.H., LL.M In this day and age, the sea not only functions as a source of human food but also as a trade route, shipping route, and as means of unifying the nation. Recent years there are lots of oil spill cases caused by human activity that has impact on marine pollution. One of the principles that can be used in solving in environmental cases is Polluter-Pays principles. Polluter pays principle is discussed in the 16th principle formulation of the Rio Declaration on Environment and Development on 2002, which provides that national authorities should endeavor to promote the internalization of environmental costs and the use of economic instruments, taking into account the approach that the polluter should, in principle, bear the costs of pollution, with due regard to the public interests and, without distorting international trade and investment. This study aims to find out the implementation of polluter pays principles in Indonesia, especially in study of oil spill, to know whether it is possible to use polluter pays principles in solving oil spill cases in Indonesian sea and to know what are the obstacles in implementing the polluter pays principle in Indonesia. This is a normative legal research, stipulate a systematic exposition by comparing the existing rules regarding on polluter pays principles and previous related cases of oil spill. The research showed polluter pays principle is very possible to be used to solve oil spill cases. Indonesian instrument that is expert to calculate the losses still does not exist so far, only the affected experts can calculate how much loss must be paid. Another obstacles that faced by Indonesia is the agency that runs law enforcement such as the Maritime Security Agency (Bakamla), the Ministry of Maritime Affairs and Fisheries (KKP), and the Ministry of Environment and Forestry (KLHK) both have the authority in enforcing environmental law that occurs at sea. Distribution of authority over environmental law enforcement that occurs at sea in Bakamla, KKP and KLHK. Training on human resources in areas adjacent to the sea in handling cases that occur at sea so that it does not take a long time to calculate how much loss so that the validity of the data obtained is more accurate. A revision to regulation No 32 of 2009 is needed in order to add clauses to the formulation or how to calculate the use of the polluter pays principle.