State laws regulating apprenticeship and slavery may give to the master of the apprentice, or of the slave, the custody of the person and the right of corporal punishment, in order the better to insure the performance of the labor due. These laws may declare that an apprentice, or a slave, who strikes his master, shall suffer death. They may provide that the testimony of an apprentice, or of a slave, shall not be received in any court of justice as evidence against his master. They may make the claims to service or labor, whether for years or for life, transferable by ordinary sale. They may declare such claims to be, under certain circumstances, of the nature of real estate. They may enact that these claims shall be hereditary, both as regards the claimant and the person held to service, so that heirs shall inherit them,--and also so that the children of apprentices, or of slaves, shall, in virtue of their birth, be apprentices or slaves. But State laws or State constitutions, whatever their provisions, cannot modify the Constitution of the United States. The Supreme Court has decided that "the Government of the Union, though limited in its power, is supreme within its sphere of action"; and again, that "the laws of the United States, when made in pursuance of the Constitution, form the supreme law of the land, anything in the constitution or laws of any State to the contrary notwithstanding."[7] [Footnote 7: "_McCulloch against the State of Maryland._" 4 Wheaton, _Rep._, p. 316.] Therefore State laws or constitutions can neither determine the interpretation of the Federal Constitution nor explain its intent. It is to be interpreted by the words, fairly and candidly construed, of its framers. In the provision under consideration the phraseology is remarkable. The word _slave_, though then in common use, to designate a negro held to service or labor for life, is not employed. It is impossible to believe that this peculiarity was accidental, or to overlook the inevitable inference from it. This provision does not recognize slavery except as it recognizes apprenticeship. African slavery, according to the expressly selected words, and therefore according to the manifest intent, of the framers of the Constitution, is here recognized as a claim to the service or labor of a negro: nothing more, nothing else.