How was the Missouri Compromise unconstitutional?

Answer:
It was only unconstitutional if you accepted Roger Taney's interpretation of the Constitution in his judgment of the Dred Scott case in 1857. He said the Constitution protected slavery - so therefore no state could declare itself to be free soil.
First answer by Jonathan Begg. Last edit by Jonathan Begg. Contributor trust: 150 [recommend contributor recommended]. Question popularity: 8 [recommend question].