Seems pretty clear to me. The Constitution also empowers the government to admit new states. Imagine the dilemma of an escaped slave living in one of the territories of the U.S. and then, upon admission of that territory as a state, finding himself bundled up and shipped back to his owner.
To me it would appear that slave owners were empowered to re-capture slaves who escaped to U.S. territories and that the federal government had no power to interfere.
Fugitive slaves by Federal law were not protected in any US state or territory.
William Tell: "To me it would appear that slave owners were empowered to re-capture slaves who escaped to U.S. territories and that the federal government had no power to interfere."
Fugitive slaves were constitutionally captured & returned from any US territory or state.
The issue here wasn't Federal "interference" but rather states' compliance with Federal law.
ML/NJ