Section II, Clause 1, of Article III provides that "The judicial power shall extend ... to all cases of admiralty and maritime jurisdiction."

Admiralty jurisdiction refers to that class of oases which are cognizable in courts established by an admiral, in that officer being vested, according to English law, the government of the King's navy and the authority to hear all causes connected with the sea, Maritime jurisdiction, as the name itself indicates, is the jurisdiction over matters relating to the sea. To a very considerable extent, then, admiralty jurisdiction and maritime jurisdiction are of like meaning. The terms are not, however, synonymous. Admiralty now has reference, primarily, to the tribunals in which the causes are tried; maritime to the nature of the causes tried. The admiralty and maritime jurisdiction of the United States is then of a double nature; that over cases depending upon acts committed upon navigable waters; and that over contracts, and other transactions connected with such navigable waters. In the former class of cases the jurisdiction is given by the locality of the act; in the latter class by the character of the act or transaction.

The cases falling within the federal admiralty jurisdiction because of the locality, i. e., arising upon the high seas and other navigable waters, are, broadly speaking, of two classes; those of prize, arising jure belli; and those acts, torts, injuries, etc., which have no reference to a state of war.

Those cases which fall within the admiralty jurisdiction purely because of their maritime nature are those arising out of contracts, claims, etc., with reference to maritime operations. In actions of tort the test determining jurisdiction is locality; in contracts, it is the subject-matter.1

1 Waring v. Clarke, 5 How. 441; 12 L. ed. 226; New Jersey Steam Navigation Co. v. Merchants' Bank, 6 How. 344; 12 L. ed. 465. The distinction between admiralty and maritime jurisdiction suggested above is not exactly that, originally at least, of the English law. See Benedict's Admiralty, ch. 4.