The Constitution, Article XIII
SEC. 1. Neither slavery nor involuntary servitude, except as a punishment for a crime whereof the party shall have been duly convicted, shall exist within the United States, or any place subject to their jurisdiction. (Ratified 1865)
Excerpt from
That in all that territory ceded by France to the United States, under the name of Louisiana, which lies north of thirty-six degrees and thirty minutes north latitude, not included within the limits of the state, contemplated by this act, slavery and involuntary servitude, otherwise than in the punishment of crimes, whereof the parties shall have
been duly convicted, shall be, and hereby, forever prohibited...
Fugitive Slave Act, 1850 SEC. 6
That when a person held to service or labor in any State or Territory of the United States, has heretofore or shall hereafter escape into another State or Territory of the United States, the person or persons to whom such service or labor may be due,...may pursue and reclaim such fugitive person, either by procuring a warrant from some one of the courts, judges, or commissioners...or by seizing and arresting such fugitive...
...it being the true intent and meaning of this act not to legislate slavery into any Territory or State, nor to exclude it therefrom, but to leave the people thereof perfectly free to form and regulate their domestic institutions in their own way, subject only to the Constitution
of the United States...
the Missouri Enabling Act, March 6, 1820. (Missouri Compromise) SEC. 8