Also known as: open sea · high seas
Written by attorneys · grounded in primary & secondary sources — see below
The open ocean beyond the territorial jurisdiction of any nation. The term identifies waters where no single country exercises sovereignty and where federal authority over commerce, piracy, and maritime offenses applies.
Orla O'Malley, a State A exporter, ships goods from a domestic port to a foreign buyer aboard a vessel that travels hundreds of miles offshore. Congress imposes a uniform duty on the cargo once the vessel enters the open seas. The duty is upheld because the shipment occurs in waters subject to federal commerce power.
Odessa Okada, captain of a foreign-flagged vessel, boards and robs another ship while both are adrift in the open seas. Federal prosecutors charge Okada with piracy under a statute defining the offense by the law of nations. The court upholds jurisdiction because the acts occurred beyond any nation's territorial limits.
Select any source to read its text and confirm it supports the definition.
Otis Olsen purchases a vessel component that fails during a voyage across the open seas, causing economic loss only. The buyer sues the manufacturer in admiralty. The court applies maritime law because the transaction and injury occurred on waters outside territorial boundaries.
Odette Orozco owns cargo aboard a vessel seized by U.S. forces while the ship sails through the open seas during declared war. The owner challenges the seizure as unauthorized. The court sustains the action because the property was taken on waters subject to federal war powers.
Oswald Orozco, a seaman injured when his vessel encountered a storm in the open seas, sues the shipowner in a U.S. district court. The owner moves to dismiss for forum non conveniens. The court retains the case because the injury occurred on waters within federal admiralty reach.
Onyx O'Reilly carries a firearm for personal protection while fishing alone in the open seas far from any state. Federal prosecutors charge a violation of a statute banning gun possession in school zones. The court dismisses the charge because the open-seas location lacks a substantial connection to interstate commerce.
Admiralty jurisdiction extends to traditional maritime activities such as ocean carriage under a bill of lading even when the precise location is the high seas. The court examines whether the claim arises from a maritime contract or tort rather than requiring proof that the event happened beyond territorial waters.
Congress possesses authority under Article I, Section 8 to define and punish piracies and felonies committed on the high seas and to regulate commerce with foreign nations. This power reaches traffic on the open seas even when both terminal ports lie within the United States.
A maritime collision on the open seas may support admiralty jurisdiction when the claim arises from traditional maritime activity, but jurisdiction still requires the plaintiff to plead facts showing navigable waters and a substantial relationship to maritime commerce. Mere assertion of state-law claims without those facts can lead to dismissal.
…offices and post roads, cl. 7, or to grant patents and copyrights, cl. 8, or to "punish Piracies and Felonies committed on the high Seas," cl. 10. It might not even need the power to raise and support an Army and Navy, cls. 12 and 13, for fewer people would engage in commercial shipping if they thought that a foreign power…