Should anyone be surprised that Heritage and DeMint are pushing false and exceptionally misleading statements about well, everything.

Slavery wasn’t ended by the federal government?

The Constitution was used to justify Dred Scott (text of the decision makes that explicit). It was used to justify the Missouri Compromise and treating African Americans as property and less than the vote of a white landed male (because at that time women weren’t entitled to vote).

It took the civil war and emancipation to make slavery disappear. The Constitution didn’t do that. It took the 13th, 14th, and 15th Amendments to overturn and negate Dred Scott. That took acts of Congress to stamp out the last vestiges of slavery, and the South has been fighting to restore the institutional racism ever since.