"There is no nation in Europe which considers itself bound to return to his master a fugitive slave, under the civil law or the law of nations. On the contrary, the slave is held to be free where there is no treaty obligation, or compact in some other form, to return him to his master. The Roman law did not allow freedom to be sold. An ambassador or any other public functionary could not take a slave to France, Spain, or any other country in Europe, without emancipating him. A number of slaves escaped from a Florida plantation, and were received on board of ship by Admiral Cochrane; by the King's Bench, they were held to be free.
In the great and leading case of Prigg v. the State of Pennsylvania, this court says that, by the general law of nations, no nation is bound to recognize the state of slavery, as found within its territorial dominions, where it is in opposition to its own policy and institutions, in favor of the subjects of other nations where slavery is organized. If it does it, it is as a matter of comity, and not as a matter of international right. The state of slavery is deemed to be a mere municipal regulation, founded upon and limited to the range of the territorial laws. This was fully recognized in Somerset's case, which was decided before the American Revolution.
"There was some contrariety of opinion among the judges on certain points ruled in Prigg's case, but there was none in regard to the great principle, that slavery is limited to the range of the laws under which it is sanctioned.
"No case in England appears to have been more thoroughly examined than that of Somerset. The judgment pronounced by Lord Mansfield was the judgment of the Court of King's Bench. The cause was argued at great length, and with great ability, by Hargrave and others, who stood among the most eminent counsel in England. It was held under advisement from term to term, and a due sense of its importance was felt and expressed by the Bench.
"In giving the opinion of the court, Lord Mansfield said:
"'The state of slavery is of such a nature that it is incapable of being introduced on any reasons, moral or political, but only by positive law, which preserves its force long after the reasons, occasion, and time itself, from whence it was created, are erased from the memory; it is of a nature that nothing can be suffered to support it but positive law.'"
In relation to the connection between the Federal Government and slavery, Judge McLean remarks:
"The only connection which the Federal Government holds with slaves in a State, arises from that provision in the Constitution which declares that 'No person held to service or labor in one State, under the laws thereof, escaping into another, shall in consequence of any law or regulation therein, be discharged from such service or labor, but shall be delivered up, on claim of the party to whom such service or labor may be due.'
"This being a fundamental law of the Federal Government, it rests mainly for its execution, as has been held, on the judicial power of the Union; and so far as the rendition of fugitives from labor has become a subject of judicial action, the federal obligation has been faithfully discharged.
"In the formation of the Federal Constitution, care was taken to confer no power on the Federal Government to interfere with this institution in the States. In the provisions respecting the slave trade, in fixing the ratio of representation, and providing for the reclamation of fugitives from labor, slaves were referred to as persons, and in no other respect are they considered in the Constitution.