I'm just going to law school at the moment, so I'm not a lawyer ... yet. Accordingly, take this with a grain of salt, if you like.
Arizona wrote this law VERY carefully. There's a TON of case law on their side of this matter. Some of it, astonishingly, comes from the 9th Circuit court. Of course this is going to go to to the Supreme Court, eventually, but in the meantime I will be quite frankly astonished if any lower court can find truly good grounds to strike the whole law down. (There's one part of it that I think is over-reaching just a bit: it's now considered trespassing for an illegal to be on any public or private land within the state of Arizona. The state can decide who is trespassing on public land ... but by [insert your favorite deity here- my own personal favorite is Crom] -I'm- the only motherfucker that gets to decide who's trespassing on my own private land. That said, I don't want any illegals in my back yard or my house, so the point is a little moot.)
Some of the relevant precedent:
In
De Canas v. Bica, 424 US 351 (1976) the Supreme Court held:
"Power to regulate immigration is unquestionably exclusively a federal power. See, e.g., [long list of cases]. But the Court has never held that every state enactment which in any way deals with aliens is a regulation of immigration and is thus pre-empted by this constitutional power, whether latent or exercised. For example Takahashi v. Fish & Game Comm'n [etc.] cited a line of cases that upheld certain discriminatory state treatment of aliens lawfully within the United States. Although the "doctrinal foundations" of the cited cases, which generally arose under the Equal Protection Clause, e.g., [blah blah], "were undermined in Takahashi," see [list of cases], they remain authority that, standing alone, the fact that aliens are the subject of a state statute does not render it a regulation of immigration, which is essentially a determination of who should or should not be admitted into the country, and the conditions under which a legal entrant may remain."
Another good one:
Chicanos
Por La Causa, Inc., v. Napolitano, 544 F.3d 976 (9th Cir. 2008).
The 9th Circuit - the most liberal of all the Federal appellate courts - held "In sum, the Act does not attempt to define who is eligible or ineligible to work under our immigration laws. It is premised on enforcement of federal standards as embodied in federal immigration law."
I could dig up more, sure, but it doesn't really change. The courts have consistently held that local / state enforcement of federal laws is concurrent enforcement, not pre-emption. Otherwise, you'd hear bloody murder raised by the Feds every time the locals arrested someone passing bad bills, or went after a kidnapper or a bank robber.
Like I said, this one will probably be decided at the level of the Supreme Court. But so far as I can tell, it SHOULD fall squarely under the concept of stare decisis, though.
Of course, at the level of the Supreme Court, it's still going to be 5-4, I think, whichever way it goes. Just like the recent 2nd Amendment case.
