John Roberts has changed. Consider the chief justice’s voting record. From 2005—the year he was appointed—until 2012—the year of the first Affordable Care Act decision—Roberts was a reliable vote on the court’s staunch conservative wing. In controversies from abortion to campaign finance to guns, Roberts sided with Justices Antonin Scalia, Clarence Thomas, Samuel Alito, and Anthony Kennedy. The 2012 health care case was the first time Roberts had ever voted with the liberal side of the court in a 5–4 decision. Lately, however, we’re seeing a very different Roberts. Last term Roberts surprised many by breaking left on a few major cases. And so far this term, Roberts has voted with Stephen Breyer (90 percent), Ruth Bader Ginsburg (85 percent), and Sonia Sotomayor (83 percent) more often than he has joined Thomas (66 percent), Kennedy (74 percent), and Alito (77 percent). And that isn’t just on minor cases. He’s recently sided with the liberals in cases on issues that typically divide the court along ideological lines, including campaign finance and anti-discrimination law.

Little wonder then that some conservatives ask if Roberts is “going wobbly.” While court watchers have recognized and speculated over Roberts’ shift to the left, the reason for the shift remains obscure. Beyond amorphous notions of Roberts’ special concerns for his “legacy” or the court’s “legitimacy,” what accounts for Roberts’ recent move to moderation? Only he truly knows the answer, but one possibility is that Roberts has learned something from his time on the bench. In particular, his transformation might have been influenced by two specific cases: one high-profile, the other largely forgotten.