Roe v. Wade polls well in broad outline, and the Supreme Court has affirmed many times its basic holding that abortion must be legal. Yet it still has a problem of democratic legitimacy. Chief Justice John Roberts, perhaps inadvertently, highlighted the problem in his controlling opinion in the court’s latest abortion case.

In our form of government, the people are supposed to be the ultimate earthly source of authority. A judicial power to set aside laws that conflict with the Constitution need not undermine this truth. The courts in such a case are giving priority to the people’s permanent will, expressed in the constitutional provisions that supermajorities of them ratified, over the transient will of majorities.

That authority and that democratic legitimacy are lacking when the courts strike down laws based on principles or policies that the people can’t plausibly be said to have ratified. So, it is in the case of abortion, the alleged right to which cannot be found in the text, original understanding, structure, history, or purpose of the Constitution.

“An exercise in raw judicial power” is what Justice Byron White, a John F. Kennedy appointee, called it in his Roe v. Wade dissent. John Hart Ely, a legal scholar who favored legal abortion, saw the defects of Roe right away, writing shortly after it was handed down in 1973, “It is bad because it is bad constitutional law, or rather because it is not constitutional law and gives almost no sense of an obligation to try to be.”

Roe’s weakness haunted Planned Parenthood v. Casey in 1992. In that decision, a plurality of the court more or less conceded that the older decision could not be justified as an interpretation of the Constitution, but upheld a modified version of it anyway on the explicit ground that “to overrule under fire” would inflict too much damage on the court’s reputation. People would stop believing “in the Court’s good faith.”

The justices expended an enormous amount of rhetorical effort to try to persuade Roe’s opponents to quit challenging it already. The Casey decision declared that Roe “calls the contending sides of a national controversy to end their national division by accepting a common mandate rooted in the Constitution.”

Millions of Americans who considered abortion a grave injustice were being asked to abandon this conviction, and not in the name of anything actually in the Constitution. They were being asked to abandon it because of something vaguely “rooted in” it. It is safe to say, 28 years later, that the gambit didn’t work.

The contending sides have kept on contending, which is how June Medical v. Russo came before the justices to be decided this term. In 2016, a bare majority of justices struck down abortion-clinic regulations in Texas. Chief Justice Roberts had voted with the dissenters that time, in Whole Woman’s Health v. Hellerstedt. This time, however, he voted to strike down Louisiana’s regulations because of respect for the 2016 precedent.

Roberts doesn’t use the high-flown rhetoric of obedience of his predecessors in Casey, but the message is similar: The people of Louisiana may want this law, they may have voted for officials who enacted this law, this law does not violate the Constitution so far as most of the justices are concerned, but still the people of Louisiana cannot have this law. They can’t have it, Roberts says, because of a 2016 decision that a majority of the justices — including Roberts! — say was in error.

The court’s abortion rulings are so malleable because they are so obviously not tethered to the Constitution.

Casey reworked Roe while reaffirming it, ditching Roe’s trimester framework and blocking only those abortion regulations that imposed an “undue burden.” In the court’s next big decision, in 2000, the authors of Casey disagreed about whether bans on partial-birth abortion were an undue burden. The court ruled they were. In 2007, the court reversed itself on that specific question. Whole Woman’s Health altered Casey while purporting to apply it: Now a regulation has to pass a cost-benefit test, too.

The unpersuasiveness of the court’s rulings wouldn’t matter if the underlying issue were an obscure one of interest only to lawyers. But millions continue to believe abortion should be forbidden. Millions more want it limited. And so, the court continues to grapple with a problem that it created but cannot solve, stuck in a trap from which it obstinately refuses to escape.

Ramesh Ponnuru is a Bloomberg Opinion columnist. He is also a senior editor at National Review.