This is going to be subject, for sure, to federal court litigation because the federal government, I believe, claims that it "preempts the field" of legislation regarding immigration.Arizona lawmakers on Tuesday passed one of the toughest pieces of immigration-enforcement legislation in the country, which would make it a violation of state law to be in the U.S. without proper documentation.
This is a thorny issue, however, because a "little known fact" (as Cliff Clavin used to say) is that there is nothing in the US Constitution that gives the federal government the authority, let alone the sole authority, to regulate immigration. Here's the Constitution - check for yourself - http://topics.law.cornell.edu/constitution - most people, left and right and center alike, assume that the federal government has the Constitutional authority to make laws about immigration - but, it's not in there. Not a peep about it.
The Supreme Court of the US weighed in in 1889 in Chae Chan Ping v. United States, where the SCOTUS said that the Congress had the inherent power to exclude aliens if it wanted to, because the preservation of US independence and security were the highest duties of the federal government, all other things being subordinate. The exclusion of aliens falls within this ambit. But, again, that's just what the Supreme Court said - it had no Constitutional basis for it. But, it also did not rule that states could also not make it illegal under state law to be in a State illegally.
So, what's the deal here - can Arizona make it an offense under Arizona law, and arrest people, who are not lawfully present in the State of Arizona?