On policy, clearly, the Supreme Court's decision on the Arizona immigration law is more of a defeat for the right than a lot of people were expecting. But in terms of November, I think it helps Mitt Romney and Republicans -- and I see that last December I predicted an outcome somewhat like this:
...I think the Court's Republicans want the lower court decision blocking provisions of the law to be upheld. Uphold the law itself and you motivate millions of Hispanic citizens to go to the polls and keep the next four years of Supreme Court vacancies out of Republican hands. By contrast, if you let the lower court decision stand, you motivate right-wing voters, who never think any institution of government is right-wing enough, and who'll therefore be more motivated to vote GOP (and the party may crave a motivation boost if its presidential nominee is less than inspiring). Fox News/talk radio wingnuts will be focused not only on the Supreme Court, but on the fact that the lower court ruling being upheld is from the hated Ninth Circuit -- the right despises the Ninth and refers to it as "the Ninth Circus." So giving Obama a win would help the GOP.The fact that three provisions of the Arizona law cherished by wingnuts would have been upheld by Antonin Scalia and Clarence Thomas, and Samuel Alito would have upheld two of them, is an alarm bell sent out to the GOP base that the courts are still dangerously left-wing (no, really) and the only remedy is another Republican presidency that will put more Scalias and Thomases on the bench (The GOP candidate, of course, is the guy who actually said the Supreme Court was liberal in 2008, in his Republican convention speech.)
The Court's right-wing justices are relentlessly corporatist, so placing curbs on an anti-immigrant jihad isn't a betrayal of their prime directive -- corporations, let's face it, like low-paid workers who can't fight back against labor abuses, and of course the Wall Street Journal editorial page used to advocate a constitutional amendment that read in its entirety, "There shall be open borders," so the elites and the Fox/talk radio rabble aren't on the same page here.
A challenge to this law wouldn't have been accepted by the Supremes on this schedule if there was a real chance that the outcome would hurt The Cause in the long run. The political impact of this was foreseen in advance.
We now know, by the way, that the chance of a Romney/Rubio ticket is zero. The base won't vote for Romney unless he positions himself as the guy who, in their eyes, will right this wrong. A Rubio pick would be worth a million votes to any third party that's hard-line on immigration.
The next big Supreme Court decision is on health care, and I'm sticking with my prediction that the mandate will go, and possibly other provisions, but the core of the law will be upheld. This makes it harder for the law to succeed in the long run and be a Democratic crowning glory, yet the law will remain on the books and motivate the base to vote for Romney.