On Monday, in a 5–4 ruling, the Supreme Court overturned a 40-year-old precedent for the simple reason that five conservative justices didn’t like it. The decision itself is unfortunate, allowing states to duck lawsuits filed against them in other states’ courts at the expense of wronged plaintiffs. But the most significant aspect of the ruling may be its cavalier treatment of precedent, which—as the dissenting justices noted in a not-so-veiled warning—signals how the majority seems to be laying the groundwork for the reversal of Roe v. Wade.

Franchise Tax Board of California v. Hyatt, Monday’s case, revolves around a California auditor’s disturbing investigation of Gilbert P. Hyatt. The California Franchise Tax Board alleged that Hyatt lied about the date of his move from California to Nevada to escape California income taxes. It sent an auditor, Sheila Cox, to his home in Nevada, where she peered through his windows, scrutinized his trash, and examined his mail. Cox allegedly became obsessed with Hyatt and vowed to “get that Jew bastard.” She enlisted his ex-wife and estranged members of his family against him. Meanwhile, the board released his address and Social Security number to several newspapers, and sent 100 letters to third parties demanding information.

The tax dispute is (somehow) still pending before the California Office of Tax Appeals. But in 1998, Hyatt sued the board in Nevada state court for its abusive actions in the course of the audit. A jury eventually awarded Hyatt $490 million in damages, which the Nevada Supreme Court reduced to $1 million. The board appealed to the U.S. Supreme Court, urging it to overrule Nevada v. Hall, a 1979 decision holding that individuals can sue a state in the courts of a different state. But after Justice Antonin Scalia died, the court split 4–4 on overturning Hall, keeping it on life support. Instead, it directed Nevada courts to apply the same damages cap to the California board that it would to a Nevada agency: $50,000.

After Justices Neil Gorsuch and Brett Kavanaugh joined the court, the California board appealed again, begging the conservative majority to kill Hall once and for all. And on Monday, in an opinion by Justice Clarence Thomas, it did just that. Throwing 40 years of precedent out the window, Thomas wrote that states have sovereign immunity from private lawsuits brought in courts of other states. Nevada courts thus have no authority to try the California board, a state agency, or impose penalties for its abuses. Hyatt is out of luck.

Thomas’ opinion is remarkable for two reasons. First, it fails to identify a specific provision in the Constitution to support this sweeping new grant of sovereign immunity. That’s because there is none. This new rule may please supporters of states’ rights—but as Justice Sonia Sotomayor noted at oral arguments, the Framers “didn’t put it in the Constitution.”

Remember these words, because they will surely be rehashed if the same five justices decide to overturn Roe.

To locate it, then, Thomas relied not on the plain text of the Constitution but upon its “history and structure.” America’s founding charter, Thomas wrote, imposed “implicit alterations to the States’ relationships with each other.” It “embeds interstate sovereign immunity within the constitutional design.” Thomas cited “numerous provisions [that] reflect this reality,” a smorgasbord of clauses that do not directly support interstate sovereign immunity. Yet taken together, he insisted, the text, history, and structure of the Constitution bestows “equal dignity and sovereignty” to states. And this sovereignty includes immunity from private lawsuits brought in other states’ courts.

It is unusual, to say the least, for conservative justices to rely upon the Constitution’s penumbras and emanations—implicit constitutional protections derived from explicit guarantees—to fashion a legal rule. But the second noteworthy aspect of Hyatt may overshadow its atextual analysis. Thomas cast aside Hall—which, again, has been the law of the land for four decades—with startling indifference. Noting that stare decisis, or adherence to precedent, is “not an inexorable command,” Thomas devoted just three paragraphs to his dismissal of Hall. The decision, he wrote, “failed to account for the historical understanding of state sovereign immunity” and “failed to consider” how the Constitution “reordered the States’ relationships with one another.” It’s also “an outlier in our sovereign immunity jurisprudence, particularly when compared to more recent decisions,” which renders it suspect.

As for the concern that Americans have relied upon Hall for 40 years? “We acknowledge that some plaintiffs, such as Hyatt, have relied on Hall,” Thomas wrote, and now “Hyatt unfortunately will suffer the loss of two decades of litigation expenses and a final judgment against the Board for its egregious conduct.” But that’s just too bad, because “in virtually every case that overrules a controlling precedent, the party relying on that precedent will incur the loss of litigation expenses and a favorable decision below. Those case-specific costs are not among the reliance interests that would persuade us to adhere to an incorrect resolution of an important constitutional question.”

Remember these words, because they will surely be rehashed if the same five justices decide to overturn Roe. In dissent, Justice Stephen Breyer acknowledged as much. Overruling precedent typically requires a “special justification,” Breyer wrote, but “the majority does not find one.” Instead, it merely decides that Hall “was wrongly decided” and should go. “The law has not changed significantly since this Court decided Hall,” Breyer pointed out, “nor has our understanding of state sovereign immunity evolved to undermine Hall.” All that has changed is the composition of the court. He added:

To overrule a sound decision like Hall is to encourage litigants to seek to overrule other cases; it is to make it more difficult for lawyers to refrain from challenging settled law; and it is to cause the public to become increasingly uncertain about which cases the Court will overrule and which cases are here to stay.

It is “dangerous,” Breyer concluded, “to overrule a decision only because five Members” of the court disagree with it. “Today’s decision can only cause one to wonder which cases the Court will overrule next.” And if there were any doubt which cases Breyer was alluding to in this dark denouement, he cited the portion of Planned Parenthood v. Casey that explained why Roe should be upheld. The justice has hoisted a red flag, alerting the country that the court’s conservative majority is preparing an assault on the right to abortion access.

At his confirmation hearings, Kavanaugh touted the importance of precedent, declaring that stare decisis is “rooted right into the Constitution itself.” He also described Roe as “precedent entitled to respect.” But on Monday, he demonstrated just how much respect he affords to precedent he disagrees with: none at all. Hall was just a few years younger than Roe and has been subjected to far less conservative criticism and attack in the lower courts. If Kavanaugh won’t uphold Hall, why should we expect him to uphold Roe? The answer, of course, is that we shouldn’t. Thomas’ opinion in Hyatt, which Kavanaugh joined in full, puts Roe in imminent danger by reducing stare decisis to a meek suggestion to be jettisoned at the majority’s whim. As Breyer implies, the court seems to be readying its rollback of Roe. The question now is just how far the conservatives will go.