I don’t see why this has to be a binary thing. That is, state and local law enforcement and civil bureaucracies don’t have to “enforce” Federal law on immigration, and they don’t even have to mount investigations as to immigration status. They probably don’t have the resources, in terms of manpower, funding or even legal / jurisdictional capability, to perform effectively in that arena. But it would seem to me that there should be some kind of “if you see something, say something” requirement that applies. When they encounter a driver at the DMV, for example, applying for a driver’s license or ID card, who presents a foreign birth certificate and no other documentation, that there should be a call put in to ICE to determine whether this person has standing to request civil services on his own behalf. There shouldn’t be a detention or other interruption of service – it would cost more to deny the application than it would to simply fulfill it – but it should be flagged for “investigation by others”. Then if the feds don’t or won’t do their jobs, the state agency can honestly say that at least they did their part, and they were in compliance regarding notification of suspicion. In the case of “actual crimes”, the line is brighter. When a person is arrested in the commission of a crime, if his immigration status is “indefinite”, then he should not be bailed out of jail until that is either established (that he is a citizen or legal resident) or, if he’s here illegally, then he can be deported forthwith. Deported by the responsible Federal authorities, that is.