THE CONSTITUTIONAL right to abortion, Donald Trump promised a few weeks before the 2016 election, would “automatically” disappear during his presidency. “I’m putting pro-life justices on the court,” he said, tantalising evangelicals and other anti-abortion voters. Three years into his first term, Mr Trump boasts two Supreme Court appointees—Justices Neil Gorsuch and Brett Kavanaugh—who are sceptical of Roe v Wade, the ruling in 1973 that legalised abortion before the fetus is able to survive outside the womb. In June Medical Services v Russo, a case being argued on March 4th, they and their three conservative brethren may take a first shot against it.

The case, brought by the Centre for Reproductive Rights on behalf of an abortion clinic in Shreveport, Louisiana, poses highly technical questions. But if its appeal is lost, the consequences could be profound, emboldening anti-abortion legislators in many states to pass new laws squeezing access to abortion.

Under discussion will be Louisiana’s Unsafe Abortion Protection Act, a law passed in 2014 with the stated aim of protecting women who choose to terminate their pregnancies. Two years after it was passed, the Supreme Court struck down an identical regulation in neighbouring Texas. Both required that abortion providers have hospital “admitting privileges”—the ability to transfer and care for patients—at a facility within 30 miles of their clinics. Acquiring these privileges is a catch-22: doctors must send a certain number of patients to a hospital each year to qualify, but abortion, being quite safe, rarely requires a hospital visit. In seeming defiance of Supreme Court precedent, Louisiana claims its rule improves vetting of abortion doctors and ameliorates clinics’ “disregard [for] basic safety standards” that “place their patients in physical danger” by, for example, making sure they are within easy reach of an emergency room, should problems occur.

These purported benefits are mere pretext, opponents say, and pale next to the burdens it places on Louisianans seeking abortion. June Medical contends that legislators’ true motivation was to limit access to abortion by making it more difficult for providers to stay open. When the bill was proposed, Katrina Jackson, a Louisiana state representative who is its primary sponsor, said the admitting-privileges requirement would save “unborn children” and “build on our past work to protect life in our state”. Bobby Jindal, the governor, was just as frank. “Promoting a culture of life in Louisiana”, he said, is “an important priority”. The Unsafe Abortion Protection Act “values human beings as unique creatures who were made by our Creator”.

When abortion providers challenged the law in 2017, a federal district court in Baton Rouge struck it down. The rule “would create substantial obstacles for women seeking abortion”, the judge concluded, “without providing any demonstrated benefit to women’s health or safety”. Several abortion doctors would be barred from continuing in their roles, leaving only one doctor in place for the entire Pelican state. This would “cripple women’s ability to have an abortion in Louisiana”, as the state’s “10,000 procedures per year” cannot possibly fall on the shoulders of a single provider.

Drawing on Planned Parenthood v Casey from 1992 and the Supreme Court’s decision in 2016 in Whole Woman’s Health v Hellerstedt—the case nullifying the same regulation in Texas—the Baton Rouge court found the law was an “undue burden” on a woman’s right to terminate her pregnancy. The short supply of clinics would make the process of procuring an abortion more fraught without any genuine benefit to women’s health. The court found no evidence that the admitting-privileges rule “would have helped even one woman obtain better treatment”.

That emphatic rejection of the law was reversed on appeal in 2018. Although the text of Louisiana’s law was identical to that of Texas, judges ruled that its impact on abortion access would be “dramatically less”. Fewer clinics would close, women would not need to drive longer distances to reach a provider and “at most, only 30% of women” would be burdened by the rule. Though “not huge”, the benefit of the law in screening abortion doctors would be sufficient to outweigh the drawbacks.

Then in February 2019 Chief Justice John Roberts joined his liberal colleagues in a 5-4 vote to block Louisiana’s admitting-privileges law from going into effect while the Supreme Court considered the question, setting the stage for this week’s hearing on the contours of abortion rights—the first such reckoning with Mr Trump’s nominees in their seats.

The Supreme Court ordinarily sticks by its previous decisions. In recent years, though, the conservative justices who form the majority have deviated from that principle in several notable cases. In 2018 they abandoned a ruling on labour-union funding that had stood since 1977; in 2019 they jettisoned a 1979 precedent involving interstate lawsuits. Rarely, though, does the Supreme Court reconsider a decision it made only a few terms ago. It would be almost unthinkable for the reconstituted majority to tear up such a fresh precedent on Whole Woman’s Health. Chief Justice John Roberts was in dissent four years ago, but as a steward of the Supreme Court’s legitimacy he could be loth to give Americans the impression that a mere change of court personnel is the key for reversing course on constitutional rights.

So although the notion of casting aside Whole Woman’s Health was floated in the Trump administration’s written filing to the justices, Chief Justice Roberts probably has other plans. One possibility is to dismiss the case on a technicality. The parties will debate not only the merits of the admitting-privileges rule but whether abortion clinics have “standing”—ie, the right—to challenge abortion regulations on their patients’ behalf. Louisiana says they do not; decades of litigation say they do.

Another possible path for Chief Justice Roberts would be to stick to the approach of the ruling that distinguished Louisiana’s law from the one in Texas, based on a review of precisely how burdensome the admitting-privileges rule would be. Although disingenuous—since the rule would, as the district court concluded, render abortion access more onerous in Louisiana—this approach could undercut the protections in Whole Woman’s Health without explicitly overruling it. Mary Ziegler, a legal historian, points out in her forthcoming book, “Abortion and the Law in America”, that the logic of Whole Woman’s Health “hardly put[s] abortion rights on safe ground”. The ruling “gave the undue burden standard more bite”, she writes, but the test remains “extraordinarily vague and subjective” and makes “each abortion case turn on its own specific facts.”

However committed the Supreme Court’s new conservative majority may be to erasing abortion rights, any demolition of Roe v Wade will not come in a bombshell decision this summer. Instead, a loss for June Medical Services would inspire a raft of underhanded abortion regulations in conservative states. Beginning in 2011, states passed nearly 500 rules dubbed TRAP (targeted regulation of abortion providers) laws by abortion-rights proponents. Whole Woman’s Health has been read by the lower courts to foreclose many of those; if that decision is overruled or undermined, anti-abortion legislators would have a freer hand to dust them off or consider new ones.

June Medical Services seems destined to hinge on the vote of Chief Justice Roberts when the decision comes down in June. He could, despite his vote in 2016, strike down Louisiana’s law as a violation of recent Supreme Court precedent. But if he sides with the four colleagues to his right, the ruling could be the first strike of a wrecking ball against Roe.