Sec.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.

Sec.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.

Sec.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.

Sec.3.  It is the duty of a nation in time of peace, to allow the people of other states a passage over its lands and waters, so far as it can be permitted without inconvenience, and with safety to its own citizens.  Of this the nation is to be its own judge.  The right of passage is only an imperfect right, because the obligation to grant the right is an imperfect obligation. (Chap.  LXIII, Sec.15.)

Sec.4.  In general, it is the duty of a nation to allow foreigners to enter and settle in the country.  On being admitted into a state, the state becomes pledged for their protection, and they become subject to its laws; and in consideration of the protection they receive, they are obliged to aid in defending it, and in supporting its government, even before they are admitted to all the rights of citizens.

Sec.5.  But no state is bound to shelter criminals fleeing into it from a foreign state.  They can be tried only in the state whose laws they have violated.  It is therefore the duty of the government to surrender a fugitive on demand of the proper authorities of the state from which he fled, if, after due examination by a civil magistrate, there shall appear sufficient grounds for the charge.  The surrender of criminals is sometimes provided for in treaties.