Meanwhile, he left much of the important work of judging undone. He muddled whether the marriage cases were based on the Constitution’s promise of equality, its protection of fundamental rights or both. He never adequately explained why, if dignity is protected by the Constitution, why similar dignity rights could not be claimed by those who want to marry more than one person or to marry a cousin. Justice Kennedy simply ignored those obvious slippery-slope problems.

Most important, he balked at declaring that laws discriminating on the basis of sexual orientation should be, like those discriminating on the basis of race or gender, presumed suspect by the courts. Much of constitutional law depends on the “levels of scrutiny.” If a law burdens a fundamental right or discriminates on the basis of race or sex, courts take a hard look to make sure the government has a really good reason for the law. Everyday laws that do not raise such problems are subject to bare “rational basis” review, and courts take only a cursory glance before moving on to the next case.

In the marriage cases, a fair analysis should have depended less on “the universal fear” of loneliness and more on whether the bans were subject to rational-basis review or something stricter. If rational, the bans should survive. If strict, they would fail. Both sides petitioned the court to rule on that question, but Justice Kennedy could not bring himself to decide it.

These doctrinal points Justice Kennedy neglected are not mere niceties. Lower courts need such guidance to determine whether laws biased against L.G.B.T. people should be upheld. Indeed, lower courts have previously read Justice Kennedy’s opaque language in Lawrence to allow states to ban gay adoption and permit governments to fire employees for engaging in private, consensual sexual behavior. The language in the marriage cases could allow similar mistakes.

President Trump’s first Supreme Court appointment, Neil Gorsuch, proved how tenuous Justice Kennedy’s pronouncements can be. Just months after Justice Gorsuch was confirmed, the court held that states cannot refuse to include the names of same-sex parents on children’s birth certificates. Same-sex couples were entitled to the entire “constellation of benefits” associated with marriage. Justice Gorsuch dissented, saying states should be free to list only biological parents. If Justice Gorsuch’s narrow view of Obergefell prevails, gays and lesbians may one day enjoy a right to marry without marriage equality.

Justice Kennedy left unanswered one of the pivotal questions for the future of gay rights: Do businesses have a right to discriminate against gay and lesbian employees or customers if the business owners claim a religious objection? The issue was teed up perfectly this term, but Justice Kennedy ultimately punted, leaving the key questions once again unaddressed. With his resignation he ensured they would be answered by a future, more conservative court more likely to see anti-gay discrimination as perfectly rational.

Back in 2010, after the Supreme Court’s decision in Citizens United overturned one of former Justice Sandra Day O’Connor’s campaign finance opinions, she lamented her retirement, saying, “Gosh, I step away for a couple of years and there’s no telling what’s going to happen.”

It may be Justice Kennedy — and those Americans who’ve found protections and respect in his decisions — with similar regrets in the years to come.