Indiana bill which would "nullify" the Affordable Care Act in the state, and make it a felony for anyone in Indiana to enforce the provisions of the ACA. Though the bill directly contravenes the Supremacy Clause of the Constitution (a fact which I will not deal with at this moment), much of the intellectual support for the bill comes out of the early 19th century doctrine of Nullification. In essence, nullification is when a State deems federal law to be unconstitutional, and therefore unenforceable, in their jurisdiction.
In support of nullification, many of the individuals whom I have talked with have pointed to states legalizing medical marijuana and/or legalizing marijuana for recreational use (Washington and Colorado). Though pointing to these states as an example of nullification may appear correct at first glance, as those states have legalized a substance that the federal government deems illegal, the argument does not support the nullification doctrine at all.
In all of the states which have legalized some form of marijuana possession, they have done so in regards to state, not federal, actors. For example, here in Michigan, a state trooper or police officer will not be able to arrest you if they catch you in possession of marijuana and you have a valid medical marijuana license. Yet, in Michigan, if a federal Drug Enforcement Agency officer pulled you over and caught you with marijuana, they WOULD be allowed to arrest you, as you have contravened federal law.
If Michigan (with its medical marijuana program) or Washington and Colorado (with their recreational use laws) had refused to allow the DEA to enforce drug laws in their states, then yes, those States would have nullified federal law. But that is not what has been done. Federal officers can, and do, go into States which allow possession of marijuana, and arrest individuals for their possession. Federal Law is still in effect, and thus, using marijuana legalization as an example of nullification taking place is, at best, a dubious method of justifying the doctrine.