nullifier

nul·li·fi·er

N0190500 (nŭl′ə-fī′ər)n.1. One that nullifies.2. One who believes in nullification as a means by which US states may resist federal laws.

Thesaurus

Noun	1.	nullifier - an advocate of nullification; someone who believes that a state can resist federal lawsadvocate, advocator, exponent, proponent - a person who pleads for a cause or propounds an idea
	2.	nullifier - an official who can invalidate or nullify; "my bank check was voided and I wanted to know who the invalidator was"invalidator, voiderfunctionary, official - a worker who holds or is invested with an office