Stephan Savoia / AP Chief Justice John Roberts, in Providence, R.I.

So much for weeks of chatter about how the Supreme Court is the last hermetic institution in Washington. CBS News has its hands on a once-in-a-lifetime scoop: someone with intimate knowledge of the court’s health care deliberations has provided an account of the decision of Chief Justice John Roberts to reverse course in May and the intense but ultimately ineffective campaign by conservative Justices to change his mind. Supreme Court leaks — especially one originating so close to the bench and coming just a few days after a ruling of such gravity — are virtually unheard of, even if all the circumstances the story describes are not.

Though conservatives seem to be taking Roberts’ flip as evidence of the Chief Justice’s squishiness — and are generally working themselves into a lather over the Bush appointee’s betrayal — switching positions late in the game is not a new phenomenon on the court. Justice Anthony Kennedy famously swapped sides in 1992’s Planned Parenthood v. Casey to uphold abortion rights, and toggles between positions more readily than most. Massimo Calabresi and David Von Drehle relayed a relevant anecdote in their recent profile of the Justice:

In one famous incident, Scalia went for a walk with Kennedy before the Casey abortion case was decided and came away from their heart-to-heart discussion confident that they would vote together. The next day, Kennedy went the other way.

This time, according to CBS News, it was Kennedy who did the lobbying. The story describes him as “relentless” until the very end, and “the most forceful and engaged of all the conservatives in trying to persuade Roberts.” That quote is telling.

I claim no inside knowledge whatsoever of the court or this story, but all leaks happen for the same reason. In a recent piece about why national-security officials give reporters classified information, Steven Aftergood wrote, “They do so not to subvert policy but to explain it, to defend it and to execute it.” In this case, it looks as if conservative members of the court felt the need to explain publicly why the decision went against them, defend their efforts to prevent the outcome and vent a little spleen.

It’s not necessarily an angry clerk gone rogue either. Former Kennedy clerk Orrin Kerr writes:

If clerks did this, it was just crazy: A clerk who leaked this and is identified has likely made a career-ending move. It’s true that a group of OT2000 clerks leaked the details of the deliberations in Bush v. Gore, and as far as I know they did not face consequences. But that was in the fall of 2004, almost four years after the decision, and my sense is that at least some of the leaking clerks were already comfy in academic jobs and no longer practicing.

CBS’s story claims knowledge of the thoughts of conservative Justices and seems to transmit their version of why Roberts flipped:

Some of the conservatives, such as Justice Clarence Thomas, deliberately avoid news articles on the court when issues are pending (and avoid some publications altogether, such as The New York Times). They’ve explained that they don’t want to be influenced by outside opinion or feel pressure from outlets that are perceived as liberal. But Roberts pays attention to media coverage. As chief justice, he is keenly aware of his leadership role on the court, and he also is sensitive to how the court is perceived by the public. There were countless news articles in May warning of damage to the court — and to Roberts’ reputation — if the court were to strike down the mandate. Leading politicians, including the president himself, had expressed confidence the mandate would be upheld.

We tried to talk him out of it, but President Obama and the liberal New York Times were just too powerful is not a narrative I imagine Roberts would endorse. Politics and public perception undoubtedly weighed on the Chief Justice (as it surely did on the rest of the court), but so did the precedent he was setting. Conservatives considered the structure of his opinion — which applied a heretofore-obscure argument that the individual mandate is a tax — ridiculous. “To say the individual mandate merely imposes a tax is not to interpret the statute, but to rewrite it,” the minority wrote. Roberts’ reply was that “every reasonable construction must be resorted to, in order to save a statute from unconstitutionality.” His vote, in theory, was for restraint of both congressional and judicial power.

That’s a lonely position, though. Conservatives are furious. Roberts’ fellow conservative jurists didn’t mention him by name in their dissent because “they no longer wished to engage in debate with him.” One Justice, according to CBS, said the right wing of the court effectively told Roberts, “You’re on your own.” They washed their hands of the ruling. Clearly, that’s something they want the world to know.