Of all the “nullification” schemes crafted by state Republicans in recent years, Missouri’s “Second Amendment Preservation Act” stood out in its over-the-top extremism.

As we discussed last summer, the proposal began by mandating that state law enforcement not enforce federal gun laws, then added the additional step of making it illegal for federal officials to enter Missouri to enforce federal gun laws. By any sane measure, the proposal was breathtakingly unconstitutional , and was predicated on a radical legal theory resolved by the U.S. Civil War.

The bill nevertheless passed the GOP-led Missouri legislature, before being vetoed by Gov. Jay Nixon (D). At the time, a Republican state senator named Brian Nieves accused the governor of “b___— slapping” the Constitution, which made no sense whatsoever.

Regardless, Nieves apparently wants to try again

A Missouri Senate panel is taking up legislation that would send federal agents to jail for enforcing federal gun control laws in the state. The measure being heard by the Senate General Laws Committee on Tuesday would declare certain federal gun control policies “null and void.” Agents enforcing them could spend a year in jail, be fined up to $1,000 and face other civil penalties.

Even in an era of Republican radicalism, this is just nuts.

This new proposal isn’t identical to the one Nixon vetoed in July, but it’s no less offensive. It would declare federal laws that “tax firearms and create a chilling effect on gun ownership, require registering or tracking of firearms or forbid the use of guns by law-abiding citizens” to be null and void in the state of Missouri.

It would be up to Missouri to decide whether federal gun laws are acceptable. If federal officials enter Missouri to enforce federal laws that Missouri doesn’t like, they would have to be accompanied by a county sheriff when executing a warrant – or face criminal charges themselves.

To be clear, this is not in a legal gray area. This isn’t a judgment call. It’s not a question that could go either way if tested in the courts. Rather, the question of whether states can reject federal laws they don’t like was decided in the middle of the 19th century – and it was a dispute the nullification crowd lost.