I will answer the question first by saying what it is not.
Nullification is not: secession, unconstitutional, untried or ineffective; for those who may be a little more familiar with American history and have remembered something from their professors or history books, it is not racist or uniquely the possession of the antebellum South.
The fact is, nullification has a considerable history in the north before the Civil War. The refusal of northern states to cooperate with the federal fugitive slave laws constituted a de facto nullification.
