Increasing numbers of states are passing laws negating, ignoring, and directly confronting federal laws. Nullification isn’t just a right-wing movement, because it’s also coming from the left on marijuana.
Kansas passed a law in April saying federal gun laws do not apply to guns manufactured and sold within Kansas. Attorney General Holder may huff and puff about this being unconstitutional and cloistered Beltway pundits sniff about how the rabble will just have to learn who is in charge because how dare they imply the federal government could be in error.
Increasing numbers of people and politicians have little faith or trust in the federal government so it’s hardly surprising nullification is becoming more popular.