> The U.S. Constitution's Supremacy Clause essentially says federal law is supreme over state law. And the preemption doctrine means that "valid federal law will always displace a state law, even a state constitutional provision that is inconsistent with that federal law," Vladeck says.
Some of the above might still be illegal under state law, of course, and those cops can arrest you for that.
But if the ATF discovers that you've committed one of the above crimes (10 year felony for each), they can still roll in and arrest you/shoot your dog. They just won't have access to local support.
The constitution restricts the federal government from infringing on the right to bear arms. It doesn't list it as an enumerated power of Congress, and the 2A only grants the power to regulate militias (and there's an argument that even the word "regulate" back then meant more to "supply/assist/resolve/provide-for" than it meant to "control").
There are some arguments re: taxation or commerce clause, but even when those clauses are used to justify un-enumerated federal laws, they don't over-ride an explicit amendment.
Exceptions that might be valid federal law fall under some other federal authority, like imports/exports, laws regulating the military, or laws that apply only to federal property, etc.