So when does a state or city law enforcement official enforce federal laws.?

Question

I can think of some.

kidnapping, bank robbery, so what federal laws are enforced.
If you go from CA or TX and your in KY you crossed state lines.

So why are not illegal aliens arrested.

Answer 1

They don't.

Only federal law enforcement can enforce federal laws.

Kidnapping is almost always a state crime -- unless it involves interstate travel, in which case it might also be federal. Bank robbery is both a state and a federal crime -- separately enforced by separate state and federal officials.

But in both examples, the state can (and does) prosecute for the state crime part of it, independent of any federal component. But the state can ONLY prosecute under the state laws -- they cannot bring charges in federal courts for violation of federal laws.

Illegal aliens who are not violating any state laws cannot be arrested by state officials unless the federal laws they are violating are felonies -- and simply failing to fill out immigration paperwork is a misdemeanor.

Answer 2

most federal laws are also duplicated in state laws. Illegal aliens violate immigration laws, which most states do not have and in which most local law enforcement have no training. They can enforce violations of state law like no ID, forgery, lying to obtain state documents, driving w/o a license etc.

Answer 3

Some local/state officers are certified to enforce immigration issues, but it does require special training, Also many local/state governments feel that it is outside their primary mission to enforce immigration laws and feel it creates a more dangerous environment for local police to enforce immigration laws as it discourages people from being witnesses or reporting crimes. There are some immigration cases in the data base available to local/state officers, but they are those who are previously deported dangerous felons or those who have failed to appear for hearings.