That doesn't mean an ICE agent can go find their ex-wife and shoot her for personal reasons.

Sure. But if he claims it was in performance of his duties, he can get away with it. Evidently. ("I thought her housekeeper was illegal, so I shot her when she told me I couldn't come inside.")

I understand the supremacy clause (or it's purpose, at least). But this seems to rely heavily on "reasonable" government and "norms". When those aren't in play, everyone is a potential victim of the government. Even you or me.

I agree that Philip's idea probably won't work. The only other solution I can see is to have the national guard meet ICE and the airport, and refuse to let them deplane. Probably not legal, either. But at least ICE can't get on the ground and start randomly killing people, which is what they're doing (at least sometimes).