After Chief Justice John Roberts Jr. sided with the four moderate liberal members of the Supreme Court to uphold the Affordable Care Act, right-wing pundits called him a traitor and left-wing pundits called him a statesman. Americans who don't generally pay attention to court decisions, but who tuned in for the health-care ruling, would therefore be excused for assuming that Chief Justice Roberts is no longer an arch-conservative but a centrist who's pulled the court to an ideological middle-ground.

But with the new term beginning on Monday, it's worth dispelling the gauzy moderate aura that the A.C.A. decision bestowed upon him and the court.

Lee Epstein and Andrew Martin, preeminent legal scholars who study the court's results from the cool perspective of political science, say the last term was little different from the previous six. The Roberts court continued as the most conservative since the anti-New Deal court of the 1930s.

John Roberts' vote in the health-care case was the sole time he joined the court's more liberal justices in any 5-4 decisions-not just in the 15 of last term, but in the 117 since he became chief justice in 2005. And his majority opinion was filled with disdainful language, what the scholar Pam Karlan in her forthcoming foreword to the Harvard Law Review's important Supreme Court issue calls "a pervasive disrespect for, and exasperation with, Congress."

That "dismissive treatment," she explains, is an expression of "lost confidence" in voters. They are also the court's constituents and they notably reciprocate the disrespect: the court's historically low standing in public opinion polls dropped even further after the health-care ruling, because, most people said, the justices on both sides had expressed political, not judicial, choices.

Professors Epstein and Martin have also brought up to date their annual analysis of the justices' ideologies-their relative conservatism or liberalism based on their voting records. The news is that Justice Samuel Alito Jr. moved even farther to the right.

It's no surprise that the upcoming presidential election could be very significant for the court. But Epstein-Martin's ideology analysis allows us to measure how different it would likely be if Mitt Romney gets to replace Ruth Bader Ginsburg compared with President Obama replacing Antonin Scalia or Anthony Kennedy.  A Roberts-Alito-like replacement for Justice Ginsburg would move the court dramatically to the right. But a Kagan-Sotomayor-like replacement for Justice Scalia or Justice Kennedy would move the court to the moderate left, with the center somewhere around Justices Elena Kagan, Sonia Sotomayor, and Stephen Breyer.

As this term begins, however, the line-up's the same as last year, and there's every reason to expect the court to continue along its conservative path.