Warships and noise regulation: The international legal framework

The use of sonar by military vessels during military exercises may produce acoustic pollution of the marine environment. States have an obligation under international law to reduce and control this form of pollution. Regulation of the use of sonar is rendered more complex by the specific regime applicable to warships, i.e. sovereign immunity. Immunity however does not prevent in all cases action by States other than the flag State, notwithstanding the limitations imposed by Art. 236 of the United Nations Convention on the Law of the Sea. More importantly, immunity does not prevent the flag State from taking measures to reduce pollution caused by its own warships. Under some environmental treaties, flag States not only may, but have the obligation to adopt measures.