MARE CLAUSUM, ma/0 kla'sfun or mii'ra klou'sum (Lat., closed sea). A sea or portion of a sea under the jurisdiction of one nation as dis tinguished from the high or open sea libe 7 not I. The two terms were used in contra,dis tinction by Grotins and Selden in time seventeenth century as time titles of their respective works, the former attacking the pretensions of Spain and Portugal to universal sovereignty, the latter in his reply (Marc Cluusum)defenIng England's claim to control over her adjacent waters.
Though as a doctrine of international law mare elausum has practically disappeared, it formed time text for the controversy finally deter mining the modern principles of maritime territo rial jurisdiction. The conditions of the ancient world rendered the sea "open to all for depreda tion;" but during the :Middle Ages the mari time powers of Europe asserted a claim to sov ereignty over those portions of the high seas ad jacent to their territories or by any assumption under their control. Thus England claimed do minion over the Channel. North Sea. the seas westward from Ireland, and more vaeuely the Bay of Biscay and the ocean north of Denmark and Sweden held the Baltic jointly. and the former disputed England's pretensions to the Icelandic- fisheries, while Venice enforeed strict sovereignty over the Adriatic. This claim was not deemed to carry with it the right of ex chiding the ships of other nations from these waters, and was supposed to involve time duty of keeping the seas free from pirates, though under the pretext of providing funds for this purpose it was sought to impose tolls on passing ships, and compensation was required for finning privi leges within the territorial zone. But with the impetus given to commerce and navigation by the discovery of the New World and the exorbitant pretensions of Spain and Portugal, whereby the former not only claimed the Pacific Ocean and the gulf of Mexico and the latter the Indian Ocean and the Atlantic Ocean south of 3.10rocco, but sought to prevent the entrance of other nations to these waters, the commercial powers of the seventeenth century revolted against these exac The predatory of Drake and Cavendish and the steadily growing trade of Hol land were the practical answer to these claims, while the jurists of the Northern nations sought theoretical justification for their acts in the doctrine of the Roman law that the (wean was incapable of appropriation.
England, however., persisted in her claim of sovereignty mer surrounding waters. In t;rotins published his treatise on More Liburum, contending, that the sea was wholly free tinder the principles of the of the civil law.
in a later work this doctrine was some what modified to permit the exception of gulfs and marginal waters that could be reduced to actual ownership. This has formed the founda tion for the modern rules of international law. In In3.5 Belden sought to defend England'. position, though maintaining that a State could not re fuse the navigation of the seas to other nations. The contest between England and Holland over the waterway, which formed the fto. Dutch emninerce resulted in the series of wars terminated by the Treaty of Westminster (10741. in which England's sovereignty was recognized from Cape to Stadland in Norway. Dur ing the eighteenth century recognition of the British flag within these waters was strenuously maintained, though the practical value of this claim gradually,?liminished. It proved, however, an insurnionntahle obstacle to the closing of ne gotiations with the ['lite(' States in I503 on the question of search, through the unwillingness of the English to surrender this right within the British Sea-. In the Admiralty Regulations thrilled that foreign ship, be re quired to 'strike their and take in their within these waters. The engrossing de mands of the Napoleonic wars. however, nullified this order, and since their close nothing has been heard of the English claim. The pretensions of Denmark during the eighteenth century shrank to a prohibition of fishing within 09 miles of oreettland and Iceland. but the diffieulty of en forcing such a rule resulted in its final surrender.
The only occasion upon which the doctrine of r/onssm stns invoked during the nineteenth eentury was in Istri by the rnited States in the vontrover-cy with f:reat Britain "ter the Bering '.?1•11 11.11erie, See Brill CONTROVERSY.
partly imemibk abandonment, hut more her:inse of the ilrineiple that maritime oceupation must be effective in order to be valid. the old doctrine of mar? elausum has been cur tailed to the assertion of territorial jurisdiction over hiclily indented or hays or other waters whose peculiar eondithois render feasible a national control. In general. such form the only I•xe?ptimi to the limit of one maritime league from the shore as laid down by llynker shoek, thong!' the principle has been nullified in practical effect by the increase in range of modern guns. Not oldt are territorial waters open to the commercial vessels of a foreign State, hut ships of war have right of 'innocent passage.' Consult the authorities referred to under INTER NATIONAL ]..sty; HIGH SEA; and BERING SEA CusTEoVERSY.