WASHINGTON — A transformed Supreme Court returns to the bench on Monday to start a momentous term in which it will consider eliminating the constitutional right to abortion, vastly expanding gun rights and further chipping away at the wall separating church and state.
The abortion case, a challenge to a Mississippi law that bars most abortions after 15 weeks, has attracted the most attention. The court, now dominated by six Republican appointees, seems poised to use it to undermine and perhaps overturn Roe v. Wade, the 1973 decision that established a constitutional right to abortion and barred states from banning the procedure before fetal viability.
The highly charged docket will test the leadership of Chief Justice John G. Roberts Jr., who lost his position at the court’s ideological center with the arrival last fall of Justice Amy Coney Barrett. He is now outflanked by five justices to his right, limiting his ability to guide the court toward the consensus and incrementalism he has said he prefers.
The chief justice, who views himself as the custodian of the court’s institutional authority, now leads a court increasingly associated with partisanship and that recent polls show is suffering a distinct drop in public support. At a time when the justices have become uncharacteristically defensive in public about the court’s record, one poll taken by Gallup last month found that only 40 percent of Americans approved of the job the court was doing, the lowest rate since 2000, when Gallup first posed the question.
“Not since Bush v. Gore has the public perception of the court’s legitimacy seemed so seriously threatened,” he said, referring to the 2000 decision in which the justices, splitting on ideological lines, handed the presidency to George W. Bush.
The recent poll followed a spate of unusual late-night summer rulings in politically charged cases. The court’s conservative majority rejected the Biden administration’s policies on asylum and evictions, and it allowed a Texas law banning most abortions after six weeks of pregnancy to go into effect. In the Texas decision, which was both procedural and enormously consequential, Chief Justice Roberts joined the court’s three Democratic appointees in dissent.
In a series of recent public appearances, several justices have insisted that their rulings were untainted by politics. Justice Barrett told an audience in Kentucky last month that “my goal today is to convince you that this court is not comprised of a bunch of partisan hacks.”
Her remarks, at the University of Louisville’s McConnell Center, came after an introduction by Senator Mitch McConnell, Republican of Kentucky and the minority leader, who helped found the center. Mr. McConnell was instrumental in ensuring Justice Barrett’s rushed confirmation just weeks after the death of Justice Ruth Bader Ginsburg and weeks before President Donald J. Trump lost his bid for re-election.
Justices Stephen G. Breyer and Clarence Thomas have in recent weeks also defended the court against charges of partisanship, saying that judicial philosophies rather than policy preferences guide its work. They added, if a little obliquely, a warning that a proposal to expand the size of the court under consideration by a presidential commission would damage the court’s authority.
On Thursday, Justice Samuel A. Alito Jr. defended the court more forcefully, saying that critics have sought to characterize it “as having been captured by a dangerous cabal that resorts to sneaky and improper methods to get its ways.”
“This portrayal,” he said, “feeds unprecedented efforts to intimidate the court and to damage it as an independent institution.”
The collective impression created by the remarks was one of defensiveness, said Mary Ziegler, a law professor at Florida State University.
“They’re aware of the same polling that everyone else is seeing that shows that the court’s popularity has fallen off pretty dramatically in recent months,” she said. “If they do things that align with partisan outcomes promised by Donald Trump on the campaign trail, people are going to view them as partisans.”
Mr. Trump, who appointed Justices Barrett, Neil M. Gorsuch and Brett M. Kavanaugh, had vowed to pick justices committed to overturning Roe v. Wade and protecting the Second Amendment.
The court last heard arguments in person more than 18 months ago, on March 4, 2020, in a case challenging a restrictive Louisiana abortion law. Justice Ginsburg was part of the five-justice majority that struck down the law that June. She died a few month later.
Chief Justice Roberts voted with what was then the court’s four-member liberal wing in that case, though he did not adopt its reasoning. More than a year later, he voted with the remaining three liberals in dissent in the abortion case from Texas.
The chief justice’s cautious support for abortion-rights precedents may continue in the Mississippi case, said Sherry F. Colb, a law professor at Cornell, though she said she did not expect his views to prevail.
“I wouldn’t have said this a few years ago, but I could imagine that Chief Justice Roberts will dissent,” she said. “Maybe he’ll even write the dissent.”
“He’s concerned about the court’s reputation and image,” Professor Colb added. “He really cares about the court as an institution.”
If there is a fifth vote for striking down the Mississippi law, it would probably come from Justice Kavanaugh, Professor Ziegler said. “Kavanaugh seems to have some concern about optics, and some concern about moving too fast,” she said. “Is he going to be like Roberts and concerned about institutional concerns and backlash?”
Carrie C. Severino, the president of the Judicial Crisis Network, a conservative group, said Chief Justice Roberts’s diminished power could be liberating.
“The biggest change is that he is not the swing vote anymore,” she said.
“You’re one of nine votes,” she said. “Vote the way you think is legally correct. There have been concerns in the past, in some cases, that that wasn’t the prime consideration. This really frees him from that temptation and that pressure.”
The coronavirus pandemic drove the justices from their courtroom for Justice Barrett’s entire first term, with the court hearing arguments by telephone. Monday will be her in-person debut in hearing arguments on the bench, sitting on the seat at its far right reserved for the junior justice.
Justice Kavanaugh, who tested positive for the coronavirus last week, will be missing. He will participate in at least the first three days of arguments “remotely from his home,” a court spokeswoman said on Friday.
The public remains barred from the courtroom, and the court will continue to provide live audio of its arguments, an innovation prompted by the pandemic that would have been hard to imagine a couple years ago.
The marquee arguments will take place in the fall. On Nov. 3, the court will consider the constitutionality of a New York law that imposes strict limits on carrying guns outside the home. The court has not issued a major Second Amendment ruling in more than a decade, and it has said next to nothing about the right to bear arms in public.
The central question in the case, New York State Rifle & Pistol Association v. Bruen, No. 20-843, has divided conservatives. Some say the right to self-defense is more acute in public. Others point to historical evidence that states have long regulated guns where people gather.
On Dec. 1, the court will hear arguments in Dobbs v. Jackson Women’s Health Organization, No. 19-1392, a challenge to a Mississippi law that seeks to ban most abortions after 15 weeks of pregnancy — about two months earlier than Roe and subsequent decisions allow.
The law, enacted in 2018 by the Republican-dominated Mississippi Legislature, banned abortions if “the probable gestational age of the unborn human” was determined to be more than 15 weeks. The statute, a calculated challenge to Roe, included narrow exceptions for medical emergencies or “a severe fetal abnormality.”
Lower courts said the law was plainly unconstitutional under Roe, which forbids states from banning abortions before fetal viability — the point at which fetuses can sustain life outside the womb, or about 23 or 24 weeks. But the case provides the newly expanded conservative majority on the Supreme Court with an opportunity to roll back or restrict the constitutional protection for abortion rights established by Roe v. Wade.
“Change is about to come with regard to abortion,” said Elizabeth W. Sepper, a law professor at the University of Texas at Austin. “I think they’re going to overrule Roe v. Wade.”
The cases on guns and abortion make the new term stand out, Professor Ziegler said.
“They’re huge,” she said. “You have two of the most explosive issues in American politics.”
But there are plenty of other significant cases on the docket. On Wednesday, for instance, the justices will hear arguments in United States v. Abu Zubaydah, No. 20-827, a case about whether the government can block a detainee at Guantánamo Bay from obtaining information from two former C.I.A. contractors involved in torturing him on the ground that it would expose state secrets.
A week later, in United States v. Tsarnaev, No. 20-443, the court will review an appeals court’s decision that threw out the death sentence of Dzhokhar A. Tsarnaev, who was convicted of helping carry out the Boston Marathon bombings in 2013.
On Nov. 1, in another death-penalty case, Ramirez v. Collier, No. 21-5592, the court will hear a request from a condemned inmate in Texas for his pastor to be able to touch him and to pray aloud with him in the death chamber.
In its last scheduled argument this year, on Dec. 8, the court will hear Carson v. Makin, No. 20-1088, a dispute over whether Maine may exclude religious schools that offer sectarian education from a state tuition program.
But it will be the Mississippi abortion case that rivets the nation. The court probably will not rule until June, as the midterm elections loom.
“There are going to be people losing their minds over this case, whichever direction it goes,” Ms. Severino said.