Editor’s Note (11/9/20): On Tuesday the Supreme Court will hear oral arguments in the case California v. Texas, which will decide whether to uphold a lower court’s ruling that the Affordable Care Act is unconstitutional because of the individual mandate to purchase health insurance. The decision, which likely will not come for several months, could strip protections for people with preexisting conditions, including COVID-19.

The death of Supreme Court Justice Ruth Bader Ginsburg—and President Donald Trump’s controversial nomination of Amy Coney Barrett to fill her seat—have ignited concerns over how a court with a six-to-three conservative majority might rule on an upcoming case on the Affordable Care Act (ACA).

The Senate Judiciary Committee is scheduled to vote on Barrett’s confirmation this Thursday. On November 10 the court will hear California v. Texas. That case will decide whether to uphold a lower court’s ruling that the ACA’s individual mandate to purchase health insurance makes the entire act unconstitutional—or to declare that the mandate is “severable” from the rest of it. If the ACA as a whole is struck down, 20 million people in the U.S. would lose their insurance. Even if it is partially struck down, up to 129 million could lose protections for preexisting conditions—including the more than eight million who have had COVID-19. If she is confirmed before the case is heard, Barrett has given no assurances that she will vote to uphold the landmark health care law.

Many legal scholars say the case for nixing the entire ACA is very weak. But even if the court severs the mandate from most of the law—as Justice Brett Kavanaugh and others have hinted—and strikes down only parts of it, that decision could still do significant damage because the ACA is so intricately tied to the health care system, a number of experts say. Invalidating the law would “throw the nation into economic chaos, in addition to people not having health insurance,” says Georges Benjamin, executive director of the American Public Health Association, a professional organization that promotes public health. “The unintended consequences of even a small tinkering of the ACA could have enormous implications.”

In 2012 the Supreme Court ruled in National Federation of Independent Business v. Sebelius that the ACA’s individual mandate was constitutional because the penalty for not being insured could be considered a tax. But in 2017 Congress passed a tax bill that lowered the penalty to $0, beginning in January 2019. As a result, Texas and other states filed a civil suit claiming the mandate was unconstitutional in 2018. A federal judge in Texas ruled that the individual mandate was unconstitutional and nonseverable, making the entire law unconstitutional—but he did not overturn it. The decision was appealed and eventually made it to the Supreme Court, which is now preparing to hear the case.

A range of different outcomes is possible, according to Katie Keith, a part-time research faculty member at the Center on Health Insurance Reforms at Georgetown University and a principal at the consulting firm Keith Policy Solutions. First, the court will have to determine whether the plaintiffs have standing to challenge the mandate. “If the answer is no, the case kind of goes away,” she says. Second, it must decide whether the mandate is constitutional or not. “Reasonable minds could disagree,” she says, but the case also goes away if the mandate is found to be constitutional. And the final question is whether the mandate is not essential to the rest of the law and can be severed from it. Keith thinks this is the most likely outcome. “We’re kind of living in that world now,” she says. “The mandate has been zero for two years, and the sky has not fallen.”

Assuming the court determines the mandate is unconstitutional and severable from some or most of the rest of the law, it would also have to decide which parts to keep. Justices Kavanaugh and John Roberts have supported the notion of severability in a previous case. This suggests they might vote to sever the mandate while keeping most of the ACA intact, Keith says. Nevertheless, she worries that some parts of the law could still be struck down—including, very importantly, the requirement that insurance companies cover preexisting conditions. That decision could affect the millions of Americans who now have, or previously had, COVID-19. Even though most cases of the disease are mild, there have been numerous reports of symptoms lingering for months after infection, as well as heart and lung damage.

COVID is “not an acute episodic disease—it has a long tail” and could therefore easily qualify as a preexisting condition, says Benjamin, who was formerly secretary of the Maryland Department of Health and Mental Hygiene, a position in which he oversaw the expansion of the state’s Medicaid program. “I would assume [COVID is] a chronic condition.” But he contends that if the justices on the court cared about access to health care, “they would care about the 20 million people who would lose health insurance” if the ACA were struck down.

Although Barrett has been tight-lipped about how she might rule on any particular case, she has criticized the court’s 2012 decision that upheld the ACA. “Obviously, the future of the ACA [would be] less secure with Judge Barrett on the court, as opposed to Ginsburg,” says Tim Jost, an emeritus professor at the Washington and Lee University School of Law. “We don’t know much about Barrett’s views on severability. She’s kind of a blank slate.”

The plaintiffs’ argument that the ACA is entirely dependent on the individual mandate is “absurd—it’s factually not true,” Jost says. “The court should look at what Congress thought it was doing in 2017,” when it reduced the mandate penalty to zero. He thinks it is clear that senators and representatives did not intend to get rid of the law entirely. “If what Congress thinks matters, [the court] should not invalidate the law,” he adds. But Barrett considers herself a textualist, someone who believes laws and the Constitution should be strictly interpreted with regard to the words used in them. “The problem with textualists,” Jost says, “is they believe ‘the law means what I say it means.’”

The ACA is an extremely complex health care law, and striking down even parts of it would be incredibly disruptive—especially in the midst of a pandemic. “Anything can happen,” Keith says. “There’s absolutely room for [the court] to strike parts of the ACA and cause some chaos.”

Read more about the coronavirus outbreak from Scientific American here. And read coverage from our international network of magazines here.