How to use "slavery" in a sentence

"I have no purpose, directly or indirectly, to interfere with the institution of slavery in the states where it exists

May Congress prohibit slavery in the Territories? The Constitution does not expressly say

MUST Congress protect slavery in the Territories? The Constitution does not expressly say.

One section of our country believes slavery is RIGHT, and ought to be extended, while the other believes it is WRONG, and ought not to be extended.