Justice Anthony M. Kennedy, 81, became known as the swing vote during the final decade of his 30 years on the Supreme Court — a description he professed to dislike.

It’s not that his ideology or positions on legal issues moved back and forth. But he would frequently cast the deciding vote on the most contentious cases.

That usually meant arguments were focused on winning Kennedy over, his words during oral arguments analyzed and overanalyzed, and his view played an outsize role in the direction of the court — and by extension, the nation’s legal landscape.

Kennedy authored landmark opinions in divisive cases, such as access to abortion, that established the law across America. He landed on the same side as the conservative wing of the court on issues including gun rights, religious freedom and campaign finance, and sided, less often, with the liberal wing on issues such as gay rights and affirmative action.

That made him a moderating force on the court.

Joshua Matz, a law clerk to Kennedy in 2014 and 2015, said the retiring justice was wrongly derided by critics for having a lack of principles when open-mindedness in his approach to each case was one of his strengths.

“He was a statesman as well as a jurist. He cared about balancing many competing forces in American life,” Matz said. “This ensured he could never be the hero of the political left or right, but so long as he remained the swing vote, it ensured that all perspectives could make their case to someone who would give it the utmost consideration.”

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Kennedy’s writing in opinions could be soaring, using passionate and aspirational language, and often focused on the dignity of Americans and how they were treated in society.

Take his opinion in a 5-4 decision in 2015 that legalized same-sex marriage, which ends with a description of same-sex couples seeking the ideals embodies by marriage such as love, fidelity, devotion, sacrifice and family.

“Their hope is not to be condemned to live in loneliness, excluded from one of civilization’s oldest institutions,” Kennedy wrote. “They ask for equal dignity in the eyes of the law. The Constitution grants them that right.”

But his decisions often drew criticism as well. For example, the late Justice Antonin Scalia criticized Kennedy’s opinion in that same-sex marriage case by equating it to “the mystical aphorism of the fortune cookie.”

Appointed amid controversy

President Ronald Reagan appointed Kennedy only after his first two picks for the vacancy faltered. The Senate voted 42-58 to reject the conservative legal intellectual powerhouse, Circuit Judge Robert Bork, in October 1987.

Two weeks later, Reagan’s next pick, solidly conservative Circuit Judge Douglas Ginsburg, withdrew from consideration after admitting he had smoked marijuana.

A Senate, weary from the Bork fight, confirmed Kennedy on a 97-0 vote in February 1988. The conservatives of the time worried about Kennedy’s past decisions and his views on privacy rights, which would factor into the landmark opinions on abortion and gay rights in which he played a key role.

Legacy upended?

Kennedy’s retirement announcement Wednesday appears to threaten the legal landscape on access to abortion, health care, voter rights, environmental law and more, according to numerous lawmakers and interest groups who weighed in.

“I was disappointed Justice Kennedy chose to retire at this point,” said Delaware Democrat Chris Coons, a Senate Judiciary member. “I think he puts his legacy at risk.”

That’s because Trump’s last appointment to the Supreme Court, Justice Neil Gorsuch, “makes clear that his ideology, his constitutional jurisprudence, his trajectory on the court is one that will inevitably conflict with some of the most important pieces of Justice Kennedy’s legacy,” Coons said.

But two areas that are most at risk are access to abortion and LGBT rights.

Kennedy wrote the opinions in a series of LGBT rights cases that, sometimes alongside major shifts in social attitudes and sometimes prompting those changes, ushered in a new era of civil rights for those groups.

Kennedy wrote the majority opinion in Romer v. Evans, the 6-3 decision in 1996 that struck down a Colorado state constitutional amendment preventing protected status for LGBT people.

Romer was the first gay rights case since the Supreme Court upheld a state criminal sodomy law in 1986 and paved the way for other gay rights cases.

Kennedy wrote the majority opinion in Lawrence v. Texas, the 6-3 decision in 2003 that struck down Texas’ sodomy laws and decriminalized same-sex acts nationwide.

He wrote the majority opinion in United States v. Windsor, the 5-4 decision in the 2013 case that struck down the Defense of Marriage Act defining marriage as between one man and one woman.

And he wrote the Obergefell v. Hodges majority opinion in 2015 that legalized same-sex marriage nationwide.

“He was the architect of four landmark decisions that helped bring LGBTQ people and their families out of the shadows and recognized their full humanity under law and in the public square,” Vanita Gupta, president of the Leadership Conference on Civil and Human Rights, said in a statement. “And he was also a swing vote against harsh criminal sentences and restrictions to reproductive healthcare for women.”

Just four years after taking the bench, Kennedy voted to uphold key parts of Roe v. Wade, the 1973 landmark Supreme Court decision that established a constitutional right to abortion. The 1992 opinion in Planned Parenthood v. Casey established that laws couldn’t create an “undue burden” on that right.

“As with any medical procedure, the State may enact regulations to further the health or safety of a woman seeking an abortion, but may not impose unnecessary health regulations that present a substantial obstacle to a woman seeking an abortion,” Kennedy’s part of the opinion stated.

The two decisions angered conservatives and gave Kennedy a reputation as a backer of abortion rights. Kennedy also wrote the 5-4 majority opinion in a 2007 case, Gonzales v. Carhart, that upheld a federal ban on “partial birth” abortion.

And in 2016, Kennedy was in a 5-3 majority that struck down provisions in Texas law to regulate abortion clinics as an undue burden on the constitutional right to abortion. The decision in Whole Women’s Health v. Hellerstedt could be read as sweeping in terms of abortion rights.

“Now that Justice Anthony Kennedy — a 25-year defender of abortion on the Supreme Court and the key vote to perpetuate Roe v. Wade — is retiring, we urge President Trump to nominate a committed constitutionalist to the Supreme Court who will hew to the intended meaning of the nation’s charter and refrain from employing it as a means of social engineering,” Catherine Glenn Foster, president of Americans United for Life, said in a statement.

Ilyse Hogue, the president of NARAL Pro-Choice America, said Kennedy’s retirement meant a “constitutional right to access legal abortion is in dire, immediate danger — along with the fundamental rights of all Americans.”

“We also know that for decades, a multi-million-dollar, extreme, anti-choice movement has quietly and aggressively chipped away at that right in state legislatures, in lower courts, and now from within the Trump administration,” Hogue said in a statement. “Their stated goal, clearly and loudly, is overturning Roe v. Wade.”