The answer would be: The republican party
The dred scott decision was created in 1857 when Dred Scott, a slave who was brought by his 'owner' to a free state where slavery is not allowed.
The supreme court decided that even though Dred Scott currently in a free state, he's still not entitled to his freedom because he is brought from non-free state.
The Republican party (which was led by Abraham Lincoln) heard about this decision and decided to oppose it.
