> Local law enforcement should not just enforce the law of the specific city they are in. They should enforce all applicable laws: city, county, state, country, etc.
Not only shouldn't they do it, they _can't_. You don't want some local sheriff deciding you're guilty of, I dunno, securities fraud, and you don't want the FBI writing parking tickets.
Police don't decide if your guilty or not.
They do need to decide how likely you are to be guilty; that's literally what probable cause is.