Los Angeles Special Response Team (SRT) within Homeland Security Investigations (HSI) of the U.S. Immigration and Customs Enforcement (ICE) prepares for raid on drug traffickers during Operation Pipeline Express. Public domain.
On March 14, Missouri governor Mike Parson signed HB 85, aka the Second Amendment Preservation Act, into law.
HB 85's first two sections can reasonably be read as "nullification" of a sort, insofar as they point out the unconstitutionality of a number of federal laws that violate the Second Amendment.
Oddly, however, the US Department of Justice seems more concerned with its third and fourth sections of the bill, which prohibit Missouri's courts and law enforcement agencies from enforcing, or assisting with the enforcement of, those unconstitutional federal laws, and allow Missourians to those who violate the prohibition to sue for damages of up to $50,000 per occurrence.
In a letter to Parson, which the Associated Press describes but which I haven't been able to find a public full-text version of, Acting Assistant US Attorney General Brian Boynton cites the US Constitution's "supremacy clause" against nullification. But his main apparent concern seems to be that the bill (AP's words, not a direct Boynton quote) " threatens to disrupt the working relationship between federal and local authorities ... noting that Missouri receives federal grants and technical assistance."
Replying to Boynton, Parson and Missouri Attorney General Eric Schmidt clarify the bill's intent: "Missouri is not attempting to nullify federal law. Instead, Missouri is defending its people from federal government overreach by prohibiting state and local law enforcement agencies from being used by the federal government to infringe Missourian's rights to keep and bear arms."
Under the Constitution, Missouri's government has every power to do that. It neither requires state governments and state employees to enforce federal laws, nor empowers the federal government to compel them to do so.
In the normal course of things, local and state law enforcement agencies assist federal law enforcement agencies with great enthusiasm.
Why? Well, money --- the "federal grants and technical assistance" that Boynton refers to in his letter. The feds spread around money (including a share of loot seized under "asset forfeiture" laws) and material (including suprlus military equipment), and that bulks up local law enforcement budgets. Cops, like everyone, enjoy better (or at least cooler) equipment and more opportunities for overtime pay.
That's a bad thing, not a good thing. It at least partially explains why 21st century America seems to be literally crawling with militarized cops. Cops wearing military utilities instead of plain vanilla police uniforms. Cops carrying M-16s instead of .38 Specials. Cops driving armored vehicles and SUVs with "Seized from Narcotics Traffickers" stickers on them instead of plain vanilla patrol cars.
Unconstitutional gun laws aren't the half of it. The war on drugs is probably a much bigger component in what amounts to a federal bribery scheme to get local cops off the job of enforcing local law and on the job of "assisting" federal thuggery of various sorts.
The Second Amendment Preservation Act is a good start, but it's just a start. If we ever want to get law enforcement back to its legitimate peacekeeping functions, state prohibitions on working with the feds should apply to everything.