[captain_dave]

I thought that a State may choose to assist in enforcing Federal law but could not be compelled to do so.

[jiggyboy]

I believe this was the opposite: the Feds wanted to prohibit Arpaio from enforcing existing Federal law.

[moehoward]

“I thought that a State may choose to assist in enforcing Federal law but could not be compelled to do so.”

In this case, it appears the plaintiff’s argument was that a policy contained in an executive order supersedes long standing law. Nonsense. That policy may dictate what course of action ICE may take since immigration is a federal matter, but MCSD holding an Illegal until notified by ICE what to do violates no law.