I honestly don't know the answer to that question. I also don't know why police haven't already been arresting these goons in Chicago and elsewhere, and I don't know all the details of this lawsuit or have time to look into it right now.
It does appear from what I've been reading elsewhere that the main effect of this ruling will be to prevent ICE from arresting people at courthouses when they show up for mandated immigration hearings and other court appearances. If so, that still sounds like an important step to me.
Cook County's top judge has signed an order barring ICE from arresting people at courthouses. Cook County includes Chicago, which has seen a federal immigration crackdown in recent months.
Detaining residents outside court has been a common tactic for federal agents, who have been stationed outside county courthouses for weeks, making arrests and drawing crowds of protesters.
More here:
https://www.cbsnews.com/chicago/news/cook-county-judge-bars-ice-agents-arrests-courthouses/
As for what the police will actually do, that remains to be seen. But I know that lawmakers and regular folks in this blue state and in the very blue city of Chicago are up in arms about what has been going on, and I'm sure that the Chicago PD, the Illinois State Police, and other LE agencies are well aware of that. I would prefer to give them a chance and see what happens, rather than assuume that they're not going to do their job.