In 2009, The New Yorker’s Jeffrey Toobin wrote that Chief Justice John Roberts, more than any of his colleagues, had “served the interests, and reflected the values, of the contemporary Republican Party.”

My, how things change.

More than a decade after he was first appointed, Roberts does not appear to be the justice he was first made out to be. That could prove pivotal in the next few years, as any of several justices may retire. We could soon see a Roberts Court in more ways than one: with him as both chief justice and swing justice, sitting at the ideological center of the bench. But what kind of court would that be? It’s relatively early in Roberts’s Supreme Court career, but he is beginning to fit the historical pattern, at least quantitatively, of an ideological defector.

The case for a liberal John Roberts starts with his 2012 decision that determined the fate of the Affordable Care Act. The chief justice was widely expected to vote to kill the law — the crown jewel of the Democratic president whom he’d sworn into office three years earlier. Instead, he performed some contorted judicial yoga, declaring that the law’s individual mandate was a constitutionally allowed tax, siding with the liberal bloc and saving Obamacare.