International Convention for the Prevention of Pollution from Ships, 1973

Article 3

Application

(1) The present Convention shall apply to:
  (a) ships entitled to fly the flag of a Party to the Convention; and
  (b) ships not entitled to fly the flag of a Party but which operate under the authority of a Party.
(2) Nothing in the present article shall be construed as derogating from or extending the sovereign rights of the Parties under international law over the sea-bed and subsoil thereof adjacent to their coasts for the purposes of exploration and exploitation of their natural resources.
(3) The present Convention shall not apply to any warship, naval auxiliary or other ship owned or operated by a State and used, for the time being, only on government non-commercial service. However, each Party shall ensure by the adoption of appropriate measures not impairing the operations or operational capabilities of such ships owned or operated by it, that such ships act in a manner consistent, so far as is reasonable and practicable, with the present Convention.