In Montana, citizens rendered a marijuana law unenforceable through jury nullification.
Recently, a man was arrested for possessing a small amount of marijuana, but the judge could not find one single person willing to sit on a jury and convict him. Unable to seat a jury, the judge was forced to give up and offer the defendant a plea deal. He got off without admitting guilt.
https://www.youtube.com/watch?v=bREOGiUVTUs
Jury nullification is when a jury or a sufficient number of jurors acquits a defendant based on the justness of the law itself, rather than the evidence determining whether the defendant actually violated it or not.
This rejection of unlawful authority is not only perfectly legal, but it did not require a single vote on either a state or federal level to take place. All it required were citizens willing to exercise such a vital tool in the defense of liberty. In fact, one might say it is the last line of defense at our disposal within our political and legal system.