What did the U.S. Constitution originally say about slavery? a. The slave trade could not be prohibited for twenty years (that is, until 1808). b. Slavery could be prohibited in the territories of the United States, but not in the states where it existed. c. Fugitive slaves who fled to other states were free by virtue of the fact that they no longer lived in slave states. d. Slavery was made legal, but masters were required to treat their slaves with civility.