United States Congress has paramount power to determine the maritime law which shall prevail throughout the country.[i]  When the Constitution was adopted, the existing maritime law became the law of the United States subject to power in Congress to alter, qualify or supplement it as and when time or experience requires.  The law administered by federal courts in admiralty is an amalgam of the general maritime law insofar as it is acceptable to the courts, modifications of that law by congressional amendment, the common law of torts and contracts as modified to the extent constitutionally possible by state legislation, and international prize law. This body of law is subject to modification by the paramount authority of Congress acting in pursuance of its powers under the admiralty and maritime clause, the necessary and proper clause, and the commerce clause.

Congress does not have power to make alterations, if admiralty jurisdiction is fixed by the constitution.  However, Congress can make changes in the absence of constitutional limitations.  The legislative power of Congress extends to jurisdictional, procedural and substantive admiralty law. 

Congress has power to define and punish piracies and felonies committed on the high seas and offenses against the law of nations, and to make rules concerning captures on land and water.  This power does not limit the Constitution’s extension of the judicial power of the federal government to cases of admiralty and maritime jurisdiction.  Congress has the power to define and punish offenses perpetrated within the admiralty and maritime jurisdiction of the United States.  This power is not limited to the territorial waters of the United States or to the high seas. Congress may grant admiralty jurisdiction of crimes committed within the territorial waters of other nations, if committed on vessels of the United States.

 Uniformity of application throughout the nation is the central purpose and feature of exclusive admiralty jurisdiction.

[i] American Bridge Co. v. The Gloria O, 98 F. Supp. 71 (D.N.Y. 1951)