Alan Caruba has an excellent article over at Warning Signs on the subject of nullifcation and its necessity. Here is an excerpt:
The great issue of our times is the same great issue of the 1830s. The question is whether Congress can pass legislation or the President issue executive orders that are not authorized by or consistent with the Constitution?
The federal government is a republic composed of separate and sovereign republics.
What recourse do the States have individually and in combination when the central government acts in a fashion that is contrary to the limits and enumerated powers of the Constitution?
The answer, other than an appeal to the courts, is nullification. This term is defined as the assertion that States can and should refuse to enforce unconstitutional federal laws.