COASTAL LEGAL STATE RESPONSES AND REMEDIESA.  Submarine SovereignImmunity

Acorollary to the doctrine of freedom of the seas is exclusive flag statecontrol over ships that fly its flag. The link between a flagstate and its craft is strongest with state government ships, which includewarships, naval auxiliaries, submarines, and ships used on non-commercialservice. As warships, submarines are protected  by sovereign immunity; while coastal statesmay have prescriptive jurisdiction over their territorial seas, they do nothave enforcement jurisdiction over foreign submarines that operate there.Coastal states lack competence to arrest, detain, or impose coercive measuresagainst foreign warships, including submarines engaged  in espionage, in order to address violationsof coastal state law.

Surfacewarships and submarines enjoy immunity from foreign jurisdiction or legalprocess, perhaps to a greater degree than other elements of the armed forces.State aircraft, such as military aircraft, also enjoy immunity from thejurisdiction of other states.368 Immunity from prescriptive andenforcement jurisdiction of another state extends to the ship and aircraft, aswell as their commanders and the crews.

The 1958 Convention on the High Seas defines awarship as “a ship belonging to thenaval forces of a state and bearing the external marks distinguishing warshipsof its nationality, under the command of an officer duly commissioned by thegovernment and whose name appears in the Navy List, and manned by a crew whoare under regular naval discipline.”370 The treaty also states“warships  on the high seas have completeimmunity from the jurisdiction of any State other than the flag State.”371The United States suggests the 1958 instrument codifies customary internationallaw.372 Likewise, Oxman’s classic study of the peacetime regime ofwarships in UNCLOS states that the principles of warship sovereign immunityderive from state practice as well as the 1958 agreements, and thereforereflect customary international law.373

The UNCLOS definition of warships includes surfacevessels and submarines of the armed forces that meet four criteria:

A ship belonging to the armedforces of a State bearing the external marks distinguishing such ships of itsnationality, under the command of an officer duly commissioned by the government of the State and whose name appears in the appropriate service listor its equivalent, and manned by a crew which is under regular armed forces discipline.374

Furthermore, Article 32 provides, “nothing inthis Convention affects the immunities of warships.”375 Oxman notesthat the article specifically refers to “the Convention” rather than “Part” or“Section,” and therefore the sovereign immunity of warships applies in allaspects of UNCLOS.376 Article 32 is in Part II of UNCLOS, whichpertains to the territorial sea and contiguous zone. The provision iscomplemented by Article 95, which is in Part VII of UNCLOS concerning the highseas, and it states emphatically that warships on the high seas have “completeimmunity” from the jurisdiction of any state except the flag state. The articlealso applies in the 200 nmEEZ of coastal states.377

In short,warship sovereign immunity applies worldwide on the high seas and in all zonesunder national jurisdiction, including the territorial sea. Warship sovereignimmunity is plenary, and it applies independently of the location of the ship.Submarines are shielded from the enforcement jurisdiction of the coastal stateeven in the territorial sea378 and internal waters of a coastalstate.379 In peacetime, submarines could enter uninvited even intothe internal waters of a foreign state without becoming subject to coastalstate jurisdiction.380 Still, submarines have a duty to comply withcoastal state law. But if they fail to do so, what recourse does the coastalstate have?