Consensus of legal scholars AND empirics agree.

In the eyes of most legal scholars, however, the efforts are unconstitutional.

“The states can’t simply choose to defy and override a valid federal law,” said Allen Rostron, a professor of constitutional law at the University of Missouri-Kansas City.

The U.S. Constitution deems federal statutes “the supreme law of the land,” Rostron said, a fact that was tested and confirmed by the Civil War. Attempts to invoke state supremacy have been shot down over the years by generations of U.S. Supreme Court decisions.

That legal view hasn’t quelled enthusiasm among conservatives. According to the National Conference of Legislatures, forms of nullification legislation have been introduced in two dozen states in recent years.

In Missouri last year, the House approved legislation making it a crime for any government official in the state to enforce the Affordable Care Act, otherwise known as Obamacare. Another bill went further, attempting to amend the state’s constitution to prohibit Missouri from recognizing or enforcing any federal law.

The Missouri bills were “patently unconstitutional,” “60 Minutes” legal analyst Andrew Cohen said in a column last year. But they were also “remarkably candid in expressing the seditious level of dissent circulating through some state legislatures.”