Sovereignty is the quality of having supreme, independent authority over a territory.  The general rule is that the sovereign and its instrumentalities cannot be sued without the consent of the sovereign.  This general rule is applicable to admiralty.[i] In a proceeding in rem, a ship is considered a person.  However, when the exemption on the ground of sovereignty is concerned, the personality of the ship cannot be severed from the sovereign to whom it belongs.[ii]

However, if there is no consent of Congress, then the U.S. is not subject to admiralty jurisdiction.  Such exemption from both admiralty jurisdiction and seizure under admiralty process are absolute for a public vessel of the U.S.  A court has no jurisdiction to determine whether the government is the rightful owner of a public vessel claimed as its own without the consent of Congress.[iii]

The doctrine of sovereign immunity embodied in the eleventh amendment [iv] bars an admiralty claim against the state.[v] In order to be exempt from admiralty process, a vessel must be solely owned by the state or its agency and it must be engaged in a governmental function.

Whereas, a vessel in the possession and service of a friendly foreign government is exempted from American admiralty jurisdiction.  Anyhow, this immunity is not extended to a merchant vessel in private possession which is owned by a foreign government.[vi] However, the exemption from admiralty jurisdiction on the ground of sovereignty can be waived by the U.S. Congress, by foreign sovereigns, and by American states.

[i] Workman v. New York City, 179 U.S. 552 (U.S. 1900)

[ii] Ex parte United States, 257 U.S. 419 (U.S. 1922)

[iii] United States v. Jardine, 81 F.2d 745 (5th Cir. Fla. 1935)

[iv] The Judicial power of the United States shall not be construed to extend to any suit in law or equity, commenced or prosecuted against one of the United States by Citizens of another State, or by Citizens or Subjects of any Foreign State.

[v] Williamson Towing Co. v. Illinois, 534 F.2d 758, 759 (7th Cir. Ill. 1976)

[vi] Republic of Mexico v. Hoffman, 324 U.S. 30 (U.S. 1945)