Joshua Roberts / Reuters

On July 9, the Fourteenth Amendment to the U.S. Constitution turns 150. On the same day, President Donald Trump will nominate a new Supreme Court justice to replace Anthony Kennedy, who, more than anyone else in America, has defined the meaning of the Fourteenth Amendment for the past three decades.

The convergence of these momentous events is appropriate. Ratified in 1868, the Fourteenth Amendment was originally intended to allow Congress and the courts to protect three fundamental values: racial equality, individual rights, and economic liberty. But the amendment was quickly eviscerated by the Court, and for nearly a century it protected economic liberty alone. Justice Kennedy embraced all three values of the Fourteenth Amendment, invoking it to protect reproductive autonomy and some forms of affirmative action, as well as to establish marriage equality, but also to limit federal economic regulations, such as the Affordable Care Act. His replacement will determine which vision of the amendment prevails for decades to come.

After the Civil War, many of the former Confederate states passed laws known as the “Black Codes,” which sharply limited the rights of former enslaved people. In response, on July 9, 1868, Congress ratified the Fourteenth Amendment, which guarantees equal protection under the law and also denies any state the right to deprive people of liberty without due process.

Only five years later, the Supreme Court eviscerated the amendment in the 5–4 Slaughterhouse Cases decision. As drafted by the Ohio congressman John Bingham, the amendment was intended to require states as well as the federal government to respect the fundamental liberties guaranteed by the Bill of Rights.

A decade later, in a lopsided 8–1 decision, the Court struck down the Civil Rights Act of 1875, which banned discrimination in public accommodations and transportation. Finally, in 1896, the Court upheld the doctrine of “separate but equal” in Plessy v. Ferguson, standing aside as the South constructed the Jim Crow regime. Justice John Marshall Harlan provided the only dissent. In one of the most famous passages in the history of Supreme Court opinions, he wrote: “There is no caste here. Our Constitution is color-blind, and neither knows nor tolerates classes among citizens. In respect of civil rights, all citizens are equal before the law. The humblest is the peer of the most powerful.”

At the same time that the Court turned away from the Framers’ vision of equal civil rights, it invoked the Fourteenth Amendment to protect economic liberties, such as freedom of contract. This period is remembered as the Lochner era, named after a 1905 decision striking down a maximum-hour law for bakers in New York. It culminated in decisions in the early 1930s that struck down the core of Franklin D. Roosevelt’s New Deal.

It wasn’t until Brown v. Board of Education in 1954 that the Court resurrected the Fourteenth Amendment’s promise of racial equality, overturning Plessy and attacking school segregation. It struck down state laws banning interracial marriage in Loving v. Virginia. And it upheld landmark civil-rights laws like the Civil Rights Act of 1964 and the Voting Rights Act of 1965. While the Court stopped short of guaranteeing equal funding for education, it did much to attack the jurisprudential foundation of Jim Crow.

At the same time, Chief Justice Earl Warren’s Court resurrected John Bingham’s vision of national enforcement of fundamental rights—most notably, by extending the protections of the Bill of Rights to the states, thereby safeguarding free speech, religious liberty, the right to counsel, and the right to be free of unreasonable searches and seizures.

More controversially, the Warren Court laid the foundation for rights not explicitly mentioned in the text of the Constitution, such as the right to privacy. In later years, the Supreme Court would build on these privacy decisions to issue decisions such as Roe v. Wade—which led to a conservative backlash against the Court.

These competing visions of economic liberty, racial equality, and personal autonomy came to a head in 1987. Justice Lewis Powell—the swing justice on Warren E. Burger’s Court—resigned. President Ronald Reagan, nearing the end of his second term, sought to place his enduring stamp on the Court by nominating the conservative legal intellectual Robert Bork. Following a bruising battle, the Senate rejected the Bork nomination, in part because he refused to recognize a constitutional right to privacy. When Anthony Kennedy embraced the right to privacy, the Senate unanimously confirmed him.

Kennedy straddled all three traditions of the Fourteenth Amendment. He was open to challenges limiting government power in the name of economic liberty: He dissented from the Court’s 5–4 decision upholding the Affordable Care Act. At the same time, Kennedy extended the reach of the Fourteenth Amendment’s protection of autonomy and privacy in landmark decisions that reaffirmed Roe and recognized the right to marriage equality. He also read key Bill of Rights protections broadly—invoking the First Amendment to strike down campaign-finance regulations in Citizens United v. FEC and extending the protections of the Second Amendment to strike down state gun regulations in McDonald v. Chicago.

Under Chief Justice John Roberts, one of the central battles over the Fourteenth Amendment has concerned affirmative action. Some conservative justices, led by Clarence Thomas, have invoked Justice Harlan’s view that “the Constitution is color-blind” to argue that all racial classifications are presumptively unconstitutional. Some liberal justices have countered that the Fourteenth Amendment was intended to ban only race-conscious policies designed to harm African Americans, not ones designed to help them. Kennedy tried to chart a middle course—upholding some affirmative-action policies (such as the University of Texas’s diversity plan) but not all.

With Kennedy leaving the Court, the future of this 150-year-old amendment is at stake. His successor will determine whether the Supreme Court interprets the amendment as allowing or prohibiting laws and policies regulating abortion, marriage, voting rights, and affirmative action. Also at stake are the scope of the Bill of Rights’ protections for free speech, gun rights, religious liberty, freedom from unreasonable government searches and seizures, and economic liberty. Strong constitutional arguments can be made for both sides of all these issues, and Justice Kennedy often held the decisive vote. His successor could determine the shape of the Fourteenth Amendment until its 200th anniversary in 2038.

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