How would a secessionist use slavery to construct an argument defending a states right to leave the union?

southern states had only ratified the constitution after an agreement with the north that slavery would never be abolished.

slavery had been listed in the declaration of independence as an unalienable right that no government could violate.

slavery had been accepted at the time of constitution when the union was created; therefore, if slavery was abolished so was the union.

if legally owned property, like slaves, could be abolished by the national government, states could secede to protect their rights.