If the SC says it is valid, would they not require an amendment to the Constitution to override it?
The SC will be deciding if the AZ law is within the constraints of existing federal statutes. Current federal law already specifically allows state and local law enforcement to assist in and perform certain immigration-associated functions.
If SCOTUS upholds the AZ law, congress could repeal those statutes with another law.
“If the SC says it is valid, would they not require an amendment to the Constitution to override it?”
Not necessarily. Congress passing a law slapping down a SCOTUS opinion would lead to what we call a “Constitutional crisis,” that is if anyone bothered to care. They’d need Obama on their side at least.
It’s happened before, what with Andy Jackson daring judges to enforce their ruling and South Carolina’s infamous nullification threat. People tend to view the former as bluster and the latter as treason. SCOTUS’ prestige as the final arbiter of the Constitution has only grown since then. Even among those who disagree with most of its decisions.
For my part, I am happy to let SCOTUS have final official say for practical purposes. Leave final final say to those who supposedly retain sovereignty, that is the people. Judicial power has probably become too entrenched to snatch back Constitutional stewardship by now. Heck, Bush the Younger wouldn’t even presume to veto a law that might be struck down by SCOTUS eventually.
It’s not as if final say is theirs by right or law, however. They have ultimate judicial authority, but judges can be wrong. Incorrect decisions are just as illegal unconstitutional laws. What do you do when SCOTUS doesn’t follow the Constitution, as they have (according to me) in too many cases to list? (Oh, okay, I’ll list a few in no particular order: Kelo, Helvering, Roe, Calder, Wickard, Dred Scott, Plessy, Butler, Home Building and Loan, Carolene Products, Bollinger, Penn Central, McConell, Buckley, Korematsu, Bennis, Miller.) Under the current balance of power, you wait until you get a different SCOTUS or you ammend the Constitution. It doesn’t have to be that way, as it’s only a compromise. Whensoever people lose the faith they’ve built up in SCOTUS as the ultimate arbitrator, that could change.