When Chief Justice John Roberts cast the deciding vote in 2012 that upheld Barack Obama’s signature achievement as president, the Affordable Care Act, he reportedly did so after a month-long campaign by fellow conservatives to persuade him to join their cause.

His decision to side with liberal colleagues enraged the right, but it also cemented the chief justice’s role as the court’s leader. That was back then.

Last week, as the Supreme Court convened for a new term that will include decisions on abortion, gun rights, and torture, Roberts lost the coveted position of sitting in the court’s ideological center. Because of the death of Ruth Bader Ginsburg and the confirmation of Amy Coney Barrett, Roberts – who has portrayed himself as a “institutionalist” seeking to protect the court’s legitimacy – no longer has the sole power to cast the deciding vote in any ruling.

Legal experts disagree on who will ultimately be seen as driving the majority’s opinions in this session, which has been described as “the most important” the court has faced in “decades” and is expected to be “tumultuous.”

The most closely watched case will involve a Mississippi law that makes abortion illegal after 15 weeks of pregnancy, which is seen as a direct challenge to Roe v Wade, the landmark decision that legalized abortion. To win any major ruling, liberals would need not only Roberts, a pro-business conservative, but also another conservative justice to join him for a 5-4 victory over the other conservatives.

“Roberts is only marginally in charge to the extent that he can bring Kavanaugh or Barrett with him,” said Josh Blackman, a law professor at the South Texas College of Law in Houston.

Clarence Thomas, the court’s most conservative member, now rules for Blackman. “I believe we are now living in Justice Thomas’ world.” “He is always thinking several steps ahead and has amassed an army of supporters,” he said. Another court watcher, Elie Mystal of the Nation, stated that it is true that conservative activists have sought to place Thomas at the center of the conservative judicial movement for decades because he has been a consistent supporter of the Republican agenda. However, his extreme views have made him an outlier.

Mystal argued that the more likely outcome would be for Neil Gorsuch to emerge as the intellectual conservative heavyweight, which would “spell doom” for liberals more often than not.

“Roberts’ ambition is to keep the law as narrow as possible while maintaining as much of the court’s legitimacy as possible while twirling ever more toward the Republicans’ agenda.” Kavanaugh enjoys beer. Amy Coney Barrett is a fan of Jesus. “These are fundamentally narrow positions,” he chuckled.

Most legal experts believe that even if conservatives do not completely overturn Roe v Wade, the abortion decision could be gutted in such a way that states could effectively make abortion illegal.

Garrett Epps, a law professor at the University of Baltimore, observed that at least two justices – Barrett and Samuel Alito – appeared “unusually defensive” in recent remarks in which both defended the court against partisanship allegations. “I think the thing to watch is whether Roberts can pick off one of the members of the [conservative] super majority and have the outcome be different than the hard right would want,” Epps said.

While Roberts is “very, very conservative,” he is not a “movement conservative,” according to Epps. He is also not motivated by what Epps described as the “rage” of some of the other justices.

According to Franita Tolson, vice dean for faculty at the University of Southern California Gould School of Law, it is unlikely that Roberts will be able to persuade any other justices to try to uphold Roe v Wade, even if he wants to.