Admiralty law (also referred to as Maritime Law) is a distinct body of law which governs maritime questions and offenses. It is a body of private international law governing the relationships between private entities which operate vessels on the oceans.
Admiralty law or maritime law is the distinct body of law (both substantive and procedural) governing navigation and shipping. Topics associated with this field in legal reference works may include: shipping; navigation; waters; commerce; seamen; towage; wharves, piers, and docks; insurance; maritime liens; canals; and recreation. Piracy (ship hijacking) is also an aspect of admiralty.
The courts and Congress seek to create a uniform body of admiralty law both nationally and internationally in order to facilitate commerce. The federal courts derive their exclusive jurisdiction over this field from the Judiciary Act of 1789 and from Article III, § 2 of the U.S. Constitution:
Article 3: Section 2
The judicial Power shall extend to all Cases, in Law and Equity, arising under this Constitution, the Laws of the United States, and Treaties made, or which shall be made, under their Authority; to all Cases affecting Ambassadors, other public Ministers and Consuls; to all Cases of admiralty and maritime Jurisdiction; to Controversies to which the United States shall be a Party; to Controversies between two or more States; between a State and Citizens of another State; between Citizens of different States; between Citizens of the same State claiming Lands under Grants of different States, and between a State, or the Citizens thereof, and foreign States, Citizens or Subjects.
In all Cases affecting Ambassadors, other public Ministers and Consuls, and those in which a State shall be Party, the supreme Court shall have original Jurisdiction. In all the other Cases before mentioned, the supreme Court shall have appellate Jurisdiction, both as to Law and Fact, with such Exceptions, and under such Regulations as the Congress shall make.
The Trial of all Crimes, except in Cases of Impeachment, shall be by Jury; and such Trial shall be held in the State where the said Crimes shall have been committed; but when not committed within any State, the Trial shall be at such Place or Places as the Congress may by Law have directed.
Congress regulates admiralty partially through the Commerce Clause:
Article 1: Section 8
To define and punish Piracies and Felonies committed on the high Seas, and Offenses against the Law of Nations;
American admiralty law formerly applied only to American tidal waters. It now extends to any waters navigable within the United States for interstate or foreign commerce. In such waters admiralty jurisdiction includes maritime matters not involving interstate commerce, including recreational boating.
Admiralty law in the United States developed from the British admiralty courts present in most of the American colonies. These courts functioned separately from courts of law and equity. With the Judiciary Act, though, Congress placed admiralty under the jurisdiction of the federal district courts. Although admiralty shares much in common with the civil law, it is separate from it. Common law does not act as binding precedent on admiralty courts, but it and other law may be used when no law on point is available.
Parties subject to admiralty may not contract out of admiralty jurisdiction, and states may not infringe on admiralty jurisdiction either judicially or legislatively. Since admiralty courts, however, are courts of limited jurisdiction (which does not extend to nonmaritime matters), 28 USC § 1333(1), the "Savings to Suitors Clause," does provide for concurrent state jurisdiction so that non-admiralty remedies will not be foreclosed. Moreover, state courts may have jurisdiction where the matter is primarily local.
Under admiralty, the ship's flag determines the source of law. For example, a ship flying the American flag in the Persian Gulf would be subject to American admiralty law; and a ship flying a Norwegian flag in American waters will be subject to Norwegian admiralty law. This also applies to criminal law governing the ship's crew. But the ship must be flying the flag legitimately; that is, there must be more than insubstantial contact between the ship and its flag, in order for the law of the flag to apply. American courts may refuse jurisdiction where it would involve applying the law of another country, although in general international law does seek uniformity in admiralty law.
Just as the Federal Rules of Civil Procedure placed law and equity under the same jurisdiction in 1938, the 1966 rules subsumed admiralty. Nonetheless, the Supplemental Admiralty Rules take precedence over the Federal Rules of Civil Procedure in the event of conflict between the two.