States' rights only count when we feel like it

Justice Antonin Scalia. Your opinions are bad
and you should feel bad
  Justice Antonin Scalia has always had a rather fast and loose opinion of the Constitution'his judicial philosophy seems to be that the Constitution says whatever the hell he says it says, and that it might very well say the opposite the next time he looks'but I don't think he's even trying, at this point. Strike that, in fact: I'm sure he's not even trying.

In Scalia's full-on wingnut dissent against striking down Arizona's SB 1070, he goes full Glenn Beck. And he pins the whole thing on states' rights, going so far as to say Arizona would never even have been created if those folks thought they would someday have disagreements with the federal government over stuff:

A good way of answering that question is to ask: Would the States conceivably have entered into the Union if the Constitution itself contained the Court's holding? Today's judgment surely fails that test. [...] If securing its territory in this fashion is not within the power of Arizona, we should cease referring to it as a sovereign State.

I believe the legal terminology for this is "booga booga booga."

Compare that with the Montana case, which the court didn't even bother to hear arguments on before deciding that Citizens United quite easily trumped any petty state-specific issues with state political improprieties and corruption. Where do states' rights figure in on that one? Nowhere. The same crowd that thought Arizona should be able to enforce whatever immigration policies they damn well felt like thought it even more self-evident that Montana did not have the same prerogative when it came to enforcing their own state anti-corruption laws. In the dissent on that case, it was Justice Breyer that mentioned that hey, maybe people grumbling about states' rights ought to at least pretend to pay attention to it here:

[E]ven if I were to accept Citizens United, this Court's legal conclusion should not bar the Montana Supreme Court's finding, made on the record before it, that independent expenditures by corporations did in fact lead to corruption or the appearance of corruption in Montana.Given the history and political landscape in Montana, that court concluded that the State had a compelling interest in limiting independent expenditures by corporations.

Well, sure, but the conservative rebuttal to Montana was get bent.

I'm not sure there's ever been a legal doctrine applied more transparently selectively than "states' rights" has been by the last few courts. It seems to only come up as binding doctrine only in those cases where Scalia, Thomas and the other conservatives have no other tool available to hang their ideologically preferred decision on. Scalia's use of it in the Arizona case is unsurprising, but the way he phrased it'apparently he's got Rush Limbaugh and Glenn Beck clerking for him now'certainly is making some legal observers wonder aloud whether Scalia has lost the plot entirely.