Ever since the federales learned to keep the states at bay with extortion and bribes using OUR tax dollars the concept has fallen into disuse. The states can once again stand in the breach for us if they but choose to do so. Whether they exercise it or not, they have a great deal of stroke under our "original" Constitution.
The union is a union of states, not people. Maybe I’m unusual, but nullification is an essential part of a federal system.
I’m rather astonished that the concept is considered to be obscure when the bloodiest war on American soil was fought over the issue.