[rockrr]

The Civil War was not fought over nullification, and as I’ve said above, at the time of the war it was the northern states that had much more recently been engaged in nullification.

Not really. Several states took a passive approach to the Fugitive Slave Act. They found the practice abhorrent and did not wish to participate.

[Nifster]

By not enforcing the fugitive slave act those ‘passive’ states were engaging in nullification