“I believe that if a state law preexists the federal law, the state law should be supreme and constitute sole jurisdiction. Gonna have to change the Constitution to get there, though.”
It depends on the charges.
A defendant can be brought up on state charges for, say, battery; then the feds can have a go at him for, say, civil rights violations. Both arising out of the same act (battery).
That’s the problem with federal overreach.