Figuring out when a mistaken precedent should govern is a notoriously tricky business. Critics of June Medical have pointed out that Roberts has previously overruled precedents that seemed at least as strong as the one he just followed. It’s true that the only way to avoid charges of inconsistency and opportunism is to take Justice Clarence Thomas’s view that clearly mistaken precedents never deserve deference. But the abortion precedents pose a particular problem, which is that they themselves don’t take precedents seriously.

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 had to pass a cost-benefit test, too, to be allowed. Roberts’s decision in June Medical goes back to Casey while pretending that Whole Woman’s Health can’t have meant what it says.

The court’s abortion rulings are so malleable because they are so obviously not tethered to the Constitution. It provides no guidance about which burdens are undue or how to weigh the benefits of an abortion regulation. So a court that claims to be following it while setting abortion policy will inevitably make up the answers and revise them as it goes.