WASHINGTON – Ketanji Brown Jackson, a former public defender who rose to become a judge on a powerful federal appeals court, made history Thursday as the first Black woman to sit on the Supreme Court.

Jackson, 51, a Miami native and Harvard-trained lawyer who was confirmed by the Senate nearly three months ago, will take the seat occupied by Associate Justice Stephen Breyer for 28 years. Breyer announced his retirement in January, clearing the way for President Joe Biden to name Jackson as his first pick for the nation’s highest court.

Previously a judge on the powerful U.S. Court of Appeals for the District of Columbia Circuit, Jackson took the oath of office at a fraught moment for the high court, as its decisions to overturn Roe v. Wade and expand access to handguns have exacerbated tensions among the justices and underscored divisions among Americans over culture war issues.

But none of that was on display as Chief Justice John Roberts administered one oath of office to Jackson and Breyer – for whom Jackson clerked more than 20 years ago – administered the other. With that, Jackson became the 104th associate justice – marking the first time women and people of color outnumber white men on the court.

“I am truly grateful to be part of the promise of our great nation,” Jackson said in a statement released by the court after the ceremony.

In brief remarks before the oaths were administered, Roberts noted that Jackson could now exercise her duties as a justice. That will allow Jackson to get her chambers and staff set up in preparation for the start of what appears to be another intense term this fall.

“I am pleased to welcome Justice Jackson to the court and to our common calling,” Roberts said.

When the justices return to Washington in October with Jackson in her seat, there will be four women and two African Americans on the nation’s highest bench for the first time in the court’s 233-year history.

“Her hard work, integrity, and intelligence have earned her a place on this court,” Breyer said in a statement released by the court. “I am glad for America. Ketanji will interpret the law wisely and fairly, helping that law to work better for the American people, whom it serves.”

Jackson was confirmed 53-47, picking up the support of three Senate Republicans along with all Democrats. Because she is replacing Breyer, who was nominated by President Bill Clinton, Jackson is not expected to change the court’s conservative tilt. Relatively young for a Supreme Court justice, Jackson could serve for decades.

“The Supreme Court just gained a colleague with a world-class intellect, the dignified temperament the American people expect of a justice, and the strongest credentials imaginable,” Biden said in a statement. “Justice Jackson’s wisdom and experience, will make all of us proud for so many years to come.”

Though Republicans largely praised Jackson’s temperament, some accused her of being soft on crime and questioned her role in defending alleged terrorists who were classified as enemy combatants after the 9/11 attacks. Though some of that criticism was sharp – unfair, according to Democrats – Jackson sailed through the hearings.

Because she sat on Harvard University’s board of overseers, Jackson announced in March that she will recuse herself from a case pending at the Supreme Court challenging the affirmative action policies at Harvard College and at the University of North Carolina. Arguments in that appeal are expected to take place in the fall.

The court will hear a number of other major cases next term, including one dealing with whether state courts may review state rules for federal elections and another on whether businesses may deny matrimonial services to same-sex couples.

Jackson will be the first former federal public defender to serve on the Supreme Court. She will be the only justice with experience on the U.S. Sentencing Commission, a bipartisan agency that makes recommendations about criminal sentences in federal court. On a court where many of her colleagues worked in presidential administrations before becoming appeals court judges, Jackson will be one of two justices – along with Associate Justice Sonia Sotomayor – to have served as a trial court judge.

Some of Jackson’s decisions drew criticism from conservatives, including a 2019 case in which she ruled that President Donald Trump’s former White House counsel, Don McGahn, had to testify as part of a congressional impeachment inquiry. She was also criticized on the right for ruling against a Trump effort to expand the number of immigrants in the country illegally who would be subjected to expedited deportation.

Those same critics rarely mentioned other cases in which Jackson sided with Trump, such as in a challenge to his controversial border wall. In another case, she ruled that federal immigration law allowed faster removals for certain migrants seeking asylum.

Jackson will arrive on the court after a historic term in which tensions between the justices spilled out into the open, a dramatic leak of a draft opinion in the abortion case undermined confidence in the court’s protocols and protests erupted in response to that leak, including some that took place outside the homes of the justices themselves.

She has quietly watched those events following her confirmation, leaving her in the unusual circumstance of being a confirmed Supreme Court justice without an actual seat on the court for months. Breyer had always intended to retire at the end of the term, but his decision became public in January, prompting Democrats – with the slimmest of majorities in the Senate – to move quickly to confirm her.

“Justice Jackson’s swearing in reflects a long overdue but welcome historic milestone,” said Elizabeth Wydra with the liberal Constitutional Accountability Center. “She will join a court at a historic crossroads, too, with two starkly different visions of the Constitution and our country represented by the conservative majority and more liberal dissenters.”