The Supreme Court embarks Monday on what could be an extraordinarily controversial term, with its justices on the defensive, its actions and structure under a political microscope and abortion — the most divisive issue of them all — taking center stage.

Before the term ends next summer, the justices will have weighed in on three major public policy disputes — guns, religious rights and possibly race, if the court takes up a request to once again review affirmative action in university admissions.

Another change on the court is possible: Justice Stephen G. Breyer, 83, nominated by President Bill Clinton, faces increasing pressure to retire while another Democrat is in the White House and the party has a tenuous hold on the Senate.

And a presidential commission on the Supreme Court, taking testimony on the court’s power and proposals to add seats to the court, limit justices’ lifetime tenure and require more transparency, is due to report to President Biden next month.

“The spotlight will be shining brighter on the court this term than perhaps any other since Bush v. Gore,” in 2000, said Pratik A. Shah, a Washington lawyer who argues before the Supreme Court.

And the background for it all will be the issue that has vexed the political and judicial branches for decades. Republican-led states and antiabortion activists are asking the court to overrule the constitutional guarantee of abortion it established nearly 50 years ago in Roe v. Wade, and reaffirmed 20 years later in Planned Parenthood v. Casey.

An upcoming Supreme Court review of a Mississippi abortion law could pave the way for many other state laws that restrict or ban the procedure. (Joshua Carroll/The Washington Post)

The narrative of the term, said Jeffrey B. Wall, former acting solicitor general for President Donald Trump, will “rise and fall” with the court’s decision on Mississippi’s law banning almost all abortions after 15 weeks. Lower courts have not allowed the law to take effect.

“If the court actually is prepared to overrule Roe and Casey, what it does on guns and affirmative action will be relatively minor wind in the sails,” Wall said at a recent preview of the term at the Georgetown Law Center.

The bold request in the Mississippi case comes before a transformed and evolving court, with three new justices, all conservatives chosen by Trump, added in the last four years.

The push by Senate Republicans to confirm Justice Amy Coney Barrett before the presidential election last fall gave right-leaning justices a 6-to-3 majority, and the ambitious agenda in her first full term on the court sets the stage for remarkable change.

There is a danger facing the court as well. “The court’s legitimacy rests on being able to show the public that a change in personnel does not mean a dramatic change of law,” Farah Peterson, a legal historian at the University of Chicago Law School, said in a teleconference. “And that’s what’s going to be at stake this term.”

Liberals already are calling on Congress to add more seats to the court to, in their view, restore ideological balance. Conservatives say warnings about the court’s legitimacy are thinly veiled attempts to intimidate the justices. Public approval for the court’s actions has dropped, according to polls.

And the extent to which the court’s internal procedures, as well as rulings, are being scrutinized became evident last week. The Senate Judiciary Committee held a hearing on the court’s processing of emergency requests that come before it, which has become known as the “shadow docket.”

The focus was the court’s 5-to-4 decision allowing Texas’s new abortion restrictions to take effect. The law bans the procedure after about six weeks of pregnancy, before most who may want the procedure will know they are pregnant. Its unique enforcement regime allows private citizens to sue doctors and others suspected of aiding and abetting those who help a patient get the prohibited procedure.

Opponents say it has forced those who want abortions to either continue an unwanted pregnancy or travel to other states to get the procedure, in effect nullifying the guarantee of Roe to choose abortion before the fetus is viable.

The controversy has embroiled Capitol Hill in partisan disagreement. More unusual has been the pushback from a number of justices in public appearances leading up to the term’s opening.

Justice Samuel A. Alito Jr., a member of the majority that let the Texas law go into effect, on Thursday delivered a 10-point rebuttal to criticism of the court’s emergency orders and the decision in the Texas case.

It was a remarkable development — justices usually do not respond in real-time to criticism. Like the Republican senators at last week’s hearing, he said there was an effort afoot to send an inappropriate warning to the court.

“The catchy and sinister term ‘shadow docket’ has been used to portray the court as having been captured by a dangerous cabal that resorts to sneaky and improper methods to get its ways,” Alito said in his speech at the University of Notre Dame. “And this portrayal feeds unprecedented efforts to intimidate the court or damage it as an independent institution.”

(The term seems to have first been used not by liberals but by William Baude, a law professor and former clerk to Chief Justice John G. Roberts Jr., to draw attention to a 2015 law review article on the court’s procedures.)

Barrett insisted in a speech that the justices were not a “bunch of political hacks.” Critics pounced on the fact she made the remarks at an event alongside her political benefactor, Senate Minority Leader Mitch McConnell (R-Ky.), at a center named for him at the University of Louisville.

Justice Clarence Thomas, at a separate event at Notre Dame, blamed the media, for making it “sound as though you are just always going right to your personal preferences. If they think you’re antiabortion or something personally, they think that’s the way you’ll always come out.”

But the dissension is also from within the court, and the extent to which those tensions reveal themselves will be one of the term’s most closely watched stories.

In the Texas case, Justice Elena Kagan practically accused her colleagues of abusing the court’s emergency process and became the first justice to use in an opinion the “shadow docket” phrasing Alito found sinister.

The court’s emergency decision-making, she said, “every day becomes more unreasoned, inconsistent, and impossible to defend.”

The Texas law, which went into effect Sept. 1 and could return to the Supreme Court, provides the backdrop to the most serious challenge to Roe that the justices have considered in decades.

On Dec. 1, they will hear Dobbs v. Jackson Women’s Health Organization, a challenge to Mississippi’s ban on almost all abortions after the 15th week of pregnancy.

Lower courts have kept the law from going into effect, saying it clearly violates Supreme Court precedents that say states cannot impose an undue burden on those seeking abortions before fetal viability, generally considered to be around 22 to 24 weeks.

When Mississippi first asked the Supreme Court to take the case, it said the court need not overturn precedent to uphold the law. The lone clinic in the state chooses not to perform abortions after 16 weeks.

But after Justice Ruth Bader Ginsburg died and Barrett took her place, the court accepted the case after months of deliberation. It limited its consideration to this question: “Whether all pre-viability prohibitions on elective abortions are unconstitutional.”

When Mississippi Attorney General Lynn Fitch (R) submitted her merits brief to the court, her answer had shifted dramatically and she said the court’s precedents should be discarded.

Roe and Casey are unprincipled decisions that have damaged the democratic process, poisoned our national discourse, plagued the law — and, in doing so, harmed this Court,” her brief states.

Doing away with the constitutional right Roe established would return the issue to the states; about a dozen have triggers that would prohibit all abortions if the decision is overturned, and others, mostly in the South and Midwest, have restrictions far earlier than viability.

Abortion providers and advocacy groups say the viability line makes sense, and is the only way the court can protect the right to abortion against ever-changing restrictions.

“Every one” of the arguments made by Mississippi and its supporters were considered by the Supreme Court in the Roe decision in 1973 and the Casey decision in 1992, said David Cole, legal director of the American Civil Liberties Union.

“The only difference between then and now is the identity of the justices,” he said.

The change in the court’s personnel also likely contributed to its acceptance of the gun case. The court on Nov. 3 will consider New York’s strict limitations on those who are permitted to carry a concealed weapon for self-defense.

After deciding in 2008 that the Second Amendment protects an individual’s right to keep a handgun in the home, the court has generally stayed away from gun control issues.

Specifically, it has left in place lower court decisions upholding state and local restrictions on the kinds of weapons permitted and restrictions on who can carry a gun outside the home, including some similar to New York’s law.

Conservative justices have complained about the court’s reticence. Barrett’s replacement of Ginsburg seems to have changed the dynamic, and the court finally will consider an effort backed by the National Rifle Association to have the court find that Second Amendment rights extend beyond the home.

Additionally, the court will continue its examination of government restrictions on spending public funds on religious organizations. It will consider Maine’s tuition-assistance program to parents who live in towns too small to have their own schools. Maine prohibits using the funds at religious schools.

The court has become much more receptive to the pleas of religious organizations, and in 2020 loosened the rules on such schools participating in state assistance programs.

With all of that, it is unclear whether the court will have the appetite to also take on a challenge to Harvard’s admission program.

The court has consistently, if narrowly, upheld a university’s right to consider race as one factor in building a diverse student body.

Lower courts have upheld Harvard’s system against charges that it unfairly benefits African American and Hispanic students and discriminates against Asian Americans.

In June, the court asked the Biden administration’s acting solicitor general to weigh in on whether it should take the case. The Trump administration had supported Harvard’s challengers in lower court, but it is likely the new administration will side with the university.

That response has not yet been filed, and the court usually takes cases through January to fill its docket for the current term.

The other unsettled question is Breyer’s future. If this is the last term for the justice confirmed in 1994, it will set up a confirmation battle in the Senate as midterm elections are held around the nation.

Biden made a campaign pledge that his first Supreme Court nominee would be the court’s first African American woman.