Urkle’s theory that immigration is strictly a federal issue may be correct but local police powers remain with the states. Thus, there should be plenty of authority for states to address this problem. Plus, the fedgov could be sued for not enforcing the laws already on the books. So this could become a nice little p!ssing match.
Actually, the Constitution only specifies that Congress provide for a uniform rule of naturalization. If you include penalties for illegal entry under this, Congress has specified that it is against the law to be in the country illegally.
Nowhere in the Constitution is it specified that anyone in the government can decide not to enforce the law. In fact, the Supremacy Clause, states that the Constitution [and the laws passed that support it] are the supreme law of the land. All government officials, judges, and States are obligated to follow it. The current law specifies penalties for illegal entry into the country.
The 10th Amendment specifies that anything not specifically reserved to the government by the Constitution [nor specifically prohibited to the states by the Constitution] is reserved to the States or the People. Law enforcement is not specifically reserved to the government and the States are bound by the Supremacy Clause to follow federal law. And the 10th Amendment allows the States to do it ...