Mandatory.
Nationwide.
Federal Law.
Now.
See there. We only had to wait minutes on it. On this issue, we have to, unfortunately give danielpalos a half right.
"Congress shall have the power to ...establish an uniform Rule of Naturalization" Article I Section 8 of the United States Constitution
"The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people." 10th Amendment to the Constitution of the United States
There is NOTHING in the Constitution that prohibits states - or the people for that matter from inviting foreigners into the United States. Congress has a very limited power here.
It's interesting that you're referring to the "state rights" when just few years back left rejected any state's jurisdiction over the immigration.
The federal government's jurisdiction over immigration law has consistently been upheld by the U.S. Supreme Court, which has overruled attempts by state legislatures to single out immigrants. Additionally, the Supremacy Clause of the U.S. Constitution is generally interpreted to mean that federal laws trump state laws, except for certain matters constitutionally left to the states.
When Arizona signed SB 1070 into law in 2010, the DOJ stated in a brief that Arizona lawmakers "crossed a constitutional line" with the new law. A federal judge blocked four of the most controversial elements, including the requirement that police check the immigration status of anyone they stop or suspect is in the state illegally.
Don't get me wrong, I think that individual states should have control over what's happening within their borders, except over citizenship and naturalization (that is federal jurisdiction), but you lefties cannot have it both way depending on who's in power.