That was what Lincoln was doing in 1861. He and his menions were usurping the Constitution to acomplish their purposes. The suspension of such rights as Habeas Corpus and jailing people simply because they did not agree with the government are just some of the many examples of a UNconstitutional government. The moralistic arguement that Slavery was wrong does not justify nor excuse the acts of Treason against the people of the states in the North as well as the southern states that were committed.
We have been living under a government since then which still today thinks that it can suspend any part of the Constitution that it does not like. The Domestic enemies of the Constitution are most often sitting in Washington D.C.