Why Did Chief Justice Roberts Vote Against AZ's Law?

The key vote in today’s Arizona immigration bill decision belonged not to Justice Anthony Kennedy – who, when it doubt, votes for what he perceives to be “personal freedom” considerations – but Chief Justice John Roberts, whom conservatives were told would reliably interpret the Constitution back during his appointment days. But Roberts was also widely known as a judicial “pragmatist” in the mold of his mentor, Chief Justice William O. Rehnquist: he was someone who could create consensus among the justices.

Today, Roberts went pragmatist rather than Constitutionalist on the Arizona bill. While more reliably originalist justices like Thomas, Scalia, and Alito voted to uphold the Arizona SB 1070 in toto, Roberts elected instead to join with Kennedy and the liberal wing – Justices Sotomayor and Breyer in this case, since Justice Kagan recused herself due to her association with the Obama administration.

Why would he do that? There are a couple rationales. First, of course, is the most obvious: Roberts agrees with Kennedy, Sotomayor and Breyer on the Constitutionality of the statute. This seems somewhat unlikely, in light of the fact that the Arizona law directly mirrored federal immigration law, and as Justice Thomas pointed out, “there is no conflict between the ‘ordinary meanin[g]’ of the relevant federal laws and that of the four provisions of Arizona law at issue here.” Roberts may believe in the so-called “purposes and objectives” theory of the supremacy clause, which holds that if the federal government seemed to want to occupy a certain field of law and pre-empt state involvement, we should read into their motives. But there’s been no evidence of that.

There is a second possibility, however, which should be more encouraging to conservatives – it is entirely possible that Roberts joined with the liberal wing on this ruling in order to provide cover for the Obamacare decision to be handed down later this week. That decision will likely be 5-4, with Kennedy as the deciding vote – and it has not been unheard-of at the Supreme Court level for a certain amount of vote-swapping to occur.

This is the problem with the Supreme Court’s power of judicial review in general – eventually, it always comes down to nine people in robes. And those people have different motivations, some political and some personal.