John Roberts' Worst Judicial Nightmare

The chief justice of the United States did not look particularly peppy when he trundled onto the bench on Tuesday. There are, of course, many reasons why John Roberts might have looked bleary-eyed and drained on that freezing morning. But I have a sneaking suspicion that the chief was disquieted by the fact that his court had just agreed to hear a legal challenge to the Obama administration's immigration executive actions--a case that, in many ways, constitutes Roberts' absolute worst nightmare.