ICE officers have no badges. They wear masks. Sometimes they have no uniforms. They grab people off the streets, and stuff them into white vans. They may send those people to foreign prisons, even if a judge tells them not to. Some of the people they take are natural-born citizens.
Taking them to court works sometimes. But ICE will often attempt to move people out of state quickly, and they won't always say where those people went. And as I mentioned above, the administration has just straight-up ignored multiple court orders.
Courts are a cute legal fiction that only works if the people with guns agree to listen to them.