Orin Kerr writes at Volokh that the cert grant in McDonald, and the question presented asking about the privileges or immunities clause, may not mean that the Court is primed to overruled Slaughter-House.

We don’t know what the Justices were thinking with any certainty. At the same time, I think there are two plausible reasons why the Court would grant cert on both issues without intending to reopen the debate over Slaughterhouse. The first is mathematical and the second is historical.

1. The first reason is the need to get to five. f the Court granted only on Due Process and left Privileges or Immunities for another day, the Court would end up with five votes against incorporation and four in favor (presumably with a concurrence by Justice Thomas saying that he might or would reach a different result if the Privileges or Immunities issue were before the Court). Then the Justices would have the problem of how to get the P or I issue before the Court again, which would ultimately lead to an 8–1 decision against incorporation by P or I. The result would be two Supreme Court opinions holding that the Second Amendment is not incorporated despite five Justices favoring incorporation.

2. A second plausible reason to grant on both issues is historical. f you’re granting cert to determine whether the Second Amendment applies to the states, and answering “yes” would effectively overturn Cruikshank and Presser, it would be a bit unusual to grant cert in a way that would make the precedents to be overturned outside the cert grant.

I find the first explanation quite plausible. Regarding the second explanation, does the Supreme Court ever overturn precedents outside the cert grant? In other words, if the Supreme Court really wanted to overturn Presser and Cruikshank, would they really be limited by the Cert Grant? In the Hillary Movie case, for example, they did not decide the case based on the initial cert grant and original oral arguments, but sent the case back with a different question presented. In my mind, if the Court wanted to overrule those precedents, such a petty formality as the question presented would seem not to cabin them.