Question

According to the Constitution, why could the federal government not decide the question of slavery?

A - The federal government could not assume powers reserved to the states.
B - The federal government could not deal with civil issues.
C- The federal government could not give that much power back to the states.
D- The federal government could not hear the testimony of slaves.
E - The federal government could not rule on personal rights issues.

Answer 1

A - The federal government could not assume powers reserved to the states.

Amendment 9: The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people.

Also it was because all the constitution writers owned slaves, but you didn't hear it from me.