§10. Although the law of nature, as expressed in the law of revelation, is a correct rule of human conduct; yet, as much of this law consists of general principles from which particular duties can not always be deduced, positive human enactments are necessary to define the law of nature and revelation. So an important part of the law of nations necessarily consists of positive institutions. Hence some writers have divided international law under these two principal heads: the natural law of nations, and the positive.
§11. The positive law of nations is founded on usage or custom and agreement, and may be considered as properly divided into the customary law of nations, and the conventional. The customary law of nations consists of certain maxims, or is founded on customs and usages which have been long observed and tacitly consented to by nations, and have thereby become binding upon all who have adopted them, so far as their observance does not require a violation of the law of nature.
§12. A conventional law of nations is one that has been established by a treaty or league. The word convention usually signifies an assembly of persons met for some benevolent, political, or ecclesiastical purpose. It also signifies a treaty, or agreement between nations; and such agreement or contract, though made without a formal meeting, is deemed conventional.
§13. As the law of nature is liable to misconstruction, and as the law of usage or custom is vague and uncertain, conventional law, because more definite, has been found to afford greater security to the rights of commerce. Hence the practice, now so common among nations, of regulating their intercourse by negotiation. By treaties, the rights of the contracting parties are placed beyond dispute.
§14. But it may be said, if each nation is independent of every other, and if there is no constituted authority to enforce the fulfillment of treaty stipulations, the rights guarantied by treaties are still insecure. But few governments are so devoid of a sense of honor as, by a palpable violation of treaty obligations, to incur the odium and condemnation of all mankind. Self-respect and the fear of provoking a war, have generally proved sufficient incentives to the observance of treaties.
§15. The obligations of nations are sometimes called imperfect. A perfect obligation is one that can be enforced--one that exists where there is a right to compel the party on whom the obligation rests to fulfill it. An imperfect obligation gives only the right to demand the fulfillment, leaving the party pledged to judge what his duty requires, and to do as he chooses, without being constrained by another to do otherwise.
Chapter LXIV.
The Jurisdiction of Nations; their mutual Rights and Obligations; the Rights of Embassadors, Ministers, &c.
§1. The seas are regarded as the common highway of nations. The main ocean, for navigation and fishing, is open to all mankind. Every state, however, has jurisdiction at sea over its own subjects in its own public and private vessels. The persons on board such vessels are protected and governed by the laws of the country to which they belong, and may be punished by these laws for offenses committed on board of its public vessels in foreign ports.
§2. The question how far a nation has jurisdiction over the seas adjoining its lands, is not clearly settled. It appears to be generally conceded, that a nation has a right of exclusive dominion over navigable rivers flowing through its territory; the harbors, bays, gulfs, and arms of the sea; and such extent of sea adjoining its territories as is necessary to the safety of the nation, which is considered by some to be as far as a cannon shot will reach, or about a marine league.