I would consider making an arrest part of enforcing the law. What I’m saying is the state should tell the feds they won’t be arresting anyone on felony warrants if the government doesn’t want the state to arrest illegal aliens.
I wouldn’t consider that any part of effectively enforcing the law, simply because a lot of people are arrested and simply let go. It happens all the time. The law isn’t enforced (at least the way I look at it) unless a case is carried through in a court of law and a person is convicted. Then it’s “enforced”.
“Arrest” is a very low bar and just about anyone can be arrested for almost anything. And so it doesn’t mean much. It means something - in terms of “enforcement” if a person is CONVICTED of a crime and there has been “due process” given and you get a guilty verdict. Then you’re talking about enforcement.