Start with its very first sentence, which grants citizenship to anyone born or naturalized on United States soil. The clause is at the core of the amendment’s meaning, yet it’s long been a favorite target for anti-immigrant Republicans in Congress and some conservative legal scholars. That movement got a lift when Donald Trump jumped aboard, claiming during the presidential campaign that “the 14th Amendment is very questionable as to whether or not somebody can come over and have a baby and immediately that baby is a citizen, O.K.?” No, not O.K. In fact, birthright citizenship, as it’s known, has long been settled law. That didn’t stop Mr. Trump, whose campaign and presidency have been built on sympathy with white nationalism, from promising that he would get it amended out of the Constitution “in my second term.”

Or take the recent, bizarre refusal by at least half a dozen of President Trump’s federal judicial nominees to go on record agreeing with one of the most esteemed Supreme Court decisions of all time — Brown v. Board of Education, which outlawed racial segregation in public schools and remains the most powerful invocation of the 14th Amendment’s Equal Protection Clause in the court’s history. The correctness of the Brown ruling is not remotely in dispute — it got high praise from three of the court’s most conservative members, Chief Justice John Roberts Jr. and Justices Samuel Alito Jr. and Neil Gorsuch, during their own confirmation hearings — yet Mr. Trump’s nominees for lower courts have declined repeatedly to say whether they think it was rightly decided. They take the same peculiar line, insisting that judicial ethics bar them from commenting on any case or issue that may come before them. That’s a prudent position to take on a live legal controversy. As a dodge to agreeing with a ruling like Brown, it’s absurd. Even if the decision is never called into doubt, it’s unnerving that they’re discussing the prospect at all.

Then there’s race-based affirmative action, which the Supreme Court has protected in recent years thanks mainly to Justice Kennedy, who wrote the 2016 decision allowing public universities to consider race as a factor in deciding which students to admit. The 14th Amendment’s framers unquestionably approved measures like these, passing laws during the same era, like the Freedmen’s Bureau Act, to give black Americans government assistance with food, clothing, jobs and education. Yet despite this history, the court’s conservatives, led by Chief Justice Roberts, believe that virtually any distinction based on race violates the Equal Protection Clause and have embraced the idea of a “colorblind Constitution” to chip away at even limited efforts to improve or maintain racial diversity in schools. It doesn’t appear to trouble them that these same arguments were raised, and lost, in congressional debates contemporaneous with passage of the 14th Amendment. If, as is nearly certain, Mr. Trump replaces Justice Kennedy with a justice who votes solidly with the other conservatives, the chief justice will have the votes to end affirmative action for good. (Mr. Trump isn’t even waiting for the court to act, asking schools on Tuesday to stop considering race altogether in making admissions decisions.)

Finally, consider the 14th Amendment’s protection of rights not listed in the Constitution itself, like a woman’s right to terminate her pregnancy or a same-sex couple’s right to marry and enjoy the benefits of marriage. Justice Kennedy was the key vote in both of these cases, and his departure creates a real risk that one or both could be significantly cut back.

On reproductive rights, he was the last remaining member of the three-justice plurality, all appointed by Republican presidents, who worked together in 1992 to save the central holding of Roe v. Wade. As recently as 2016, Justice Kennedy sided with the court’s liberals in striking down onerous state restrictions on abortion.

He was also the court’s most consistently eloquent voice in support of the equal rights of gays and lesbians, writing every landmark opinion on the issue for 20 years. The court’s growing right flank appears to have little appetite for honoring the broader implications of those rulings.

The Reconstruction Amendments — the 13th, 14th and 15th — are rightly considered the nation’s second founding, the beginning of a centuries-long effort to cleanse America of its original sin and to continue the work of perfecting the union. Interpreting the 14th Amendment in light of its history and original meaning — a method the conservative justices swear by in most other cases — should lead the Supreme Court to wield it much more aggressively than it has. But as an increasingly hard-right majority settles in, it’s reasonable to fear that the court will move in the wrong direction for years to come.