Transboundary environmental damage is on the increase internationally. Sectoral environmental liability regulations exist for many areas, such as the protection of the marine environment, water protection or oil spills. However, their conditions for liability often vary, which in some fields may lead to regulatory disparities or regulatory gaps. The authors have compiled and analysed a large part of existing international environmental liability regulations, which in the majority of cases are based on multilateral environmental conventions and jurisdiction. The study also compiles key components of existing international, European and national liability systems and identifies the main elements of consistent international environmental liability. According to the authors, the subsidiary and supplementary responsibility of states which is embodied in European law can be used to improve liability systems. This envisages a liability of states where they fail to transpose international environmental protection regulations into national law and do not reduce the risk of environmental damage. The principle that the polluter is liable for environmental damage he or she has caused would thus apply not only to private persons, but also to the public sector and states.