But stuff like this..... Arizona's desire to do something about the problem is understandable, but this law is just amateurish. As the opinion points out, Arizona's arguments in court were essentially an attempt to explain why what the law meant was different from the actual letter of the law.
There's certainly that, but there's also this "sanctuary" issue as well. And, it's kind of a pickle for the states to manage, given this decision.
While there's a supremacy clause that applies from federal t state, there's also the public policy necessity for states to be able to give binding direction to their municipalities. How can states stop these cities from giving safe-harbor, even explicit safe-harbor to illegals if the state can't craft any legislation that specifically addresses the issue without encroaching on the federal government's foreign policy supremacy?
Given this decision, it seems likely that Tuscon, for example, can continue to provide unrestrained support to people who should be deported, and who are knowingly deportable. That's a problem - and it's a problem that becomes more difficult to remedy with this decision.
The FedGov needs to enact legislation that demands that state/local police officers act accordingly if there's reasonable suspicion that they've come in contact with an illegal. Then, they can litigate that federal statute without any supremacy clause issues.