But it does mean that you can't use state law to to make it harder for ICE to perform their functions the way Philip was suggesting. If the rule actually limits their ability to do these raids in any material way, then the rule has to give way to the federal objective.

The only way to know if a federal agent is executing their duties when killing an unarmed person is to arrest them for the crime and take them to court. You are suggesting that the very questioning of the act as murder or duty is beyond state adjudication as it has ALREADY been adjudicated under the supremacy clause. You have preempted action by declaring state authority to investigate potentially criminal federal behavior as constitutionally prohibited. Only the Feds can decide to investigate crimes committed by federal agents.

As a lawyer who believes in the wheels of justice, why preemptively preclude those wheels from being put in motion?

Let states execute their laws through effective law enforcement, and let the courts determine the constitutionality of that law enforcement activity.