Joshua Roberts / Reuters

Like everyone who follows the Supreme Court, I’ve been trying to read Justice Anthony Kennedy’s mind for more than 30 years. I was an intern for Joe Biden on the Senate Judiciary Committee the summer that Robert Bork’s nomination to the Supreme Court was defeated in 1987, and watched Senator Biden turn from an opponent of Bork to a supporter of Kennedy because of Kennedy’s belief that Americans have natural rights, like privacy, that come from God rather than Government. Biden’s support of Kennedy was prescient. Kennedy proved on the Court to be the most significant exponent of a natural-rights jurisprudence of this era, expanding the right to privacy to reaffirm the core of Roe v. Wade, which legalized abortion, while extending his broad vision of constitutional liberty to protect marriage equality and to question the health-care mandate of the Affordable Care Act.

“At the heart of liberty is the right to define one’s own concept of existence, of meaning, of the universe, and of the mystery of human life,” Kennedy wrote in his 1992 decision upholding the core of Roe. The late Justice Scalia ridiculed this as the “sweet mystery of life passage”; and it seemed to reflect the judicial vision of the liberal legal philosopher Ronald Dworkin rather than James Madison. It was hard, in other words, to root in the text or original understanding of the Constitution. But it represented the core of a libertarian jurisprudence—one book about Kennedy is called The Tie Goes to Freedomthat deserves respect for its refusal to abide by partisan political labels, and for its devotion to keeping the government within the limits defined by the Constitution.

It’s not a surprise that Kennedy voted to strike down more federal and state laws over a period of decades than any other liberal or conservative justice. He was the most enthusiastic advocate of principled judicial engagement, and now that progressives as well as conservatives are rediscovering the virtues of invoking the Constitution to check the president and Congress, his willingness to check populist threats to liberty is being properly celebrated by both sides.

Over the course of his three decades on the Court, I wrote several pieces expressing frustration with Kennedy’s self-dramatizing quality. An early interview called him “The Agonizer”; a later one objected to his judicial arrogance.

Taking his career as a whole, however, I think these appraisals were too harsh. Kennedy was an idealist, a patriot, and a lover of the Constitution, who believed fervently that the greatest document of freedom ever written provides a framework for citizens of different perspectives to agree and disagree with each other in civil terms.

It’s also significant that Kennedy expressed thanks in his retirement letter “for having had the privilege to seek in each case how best to know, interpret, and defend the Constitution and the laws that must always conform to its mandates and promises.” That combination of “mandates and promises” was characteristic of Kennedy: He thought American officials have an obligation not only to respect the Constitution and the law but also to respect the promise of American ideals.

All of the justices on the Roberts Court are devoted, in their own ways, to enforcing their own views of what the Constitution allows and prohibits. What made Kennedy distinctive was his idealistic commitment to an America where civil agreement and disagreement was possible, and where civic education could ensure an engaged citizenry, ready, willing, and able to defend liberty. The law professor Akhil Amar has called the sunny Californian a combination of Jimmy Stewart, Ronald Reagan, and Earl Warren, whom Kennedy knew as a child. He was a passionate supporter of civic education, urging citizens to visit the National Constitution Center in Philadelphia and online, emphasizing that “the Center in its many dimensions must remind us to seek always to find new ways to teach the meaning of the Constitution and the freedom it secures.” He developed a reading list for young people called  “Understanding Freedom’s Heritage: How to Keep and Defend Liberty,” beginning with Pericles’s funeral oration and ending with his own opinion in Lawrence v. Texas, which struck down laws against homosexual sex. He understood, with Jefferson, that democracy cannot survive ignorant and free.

Kennedy’s replacement with one of the able nominees on President Trump’s list—all more conservative, and more originalist than he—will transform the Court as dramatically as Robert Bork would have if Bork, rather than Kennedy, had been confirmed in 1987. Some of the transformations may be less dramatic, in practice, than liberals fear; a decade ago, I wrote a piece for this magazine imagining what would happen the day after Roe were overturned; Justice Ginsburg has subsequently confirmed that the main effect would be restricting the access of poor women who have little access today.

There will be plenty of time to assess the impact of Kennedy’s successor on the Constitution and the law. On the day of his retirement, Kennedy deserves America’s thanks for believing that all citizens, regardless of party or faction, can unite around the ideals Americans share, rooted in the U.S. Constitution.

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