This has not been a quiet term for the Supreme Court, to put it mildly. But shortly before Christmas, the justices added yet another set of high-profile cases to their docket: two cases that deal with the legality of President Biden’s COVID-19 vaccine mandates. Oral arguments in the cases, which involve a vaccination requirement for some health care workers and a vaccine-or-testing requirement for large employers, will take place on Friday.

It’s not clear where the justices might land, either. On the one hand, there’s no reason to think that the conservative justices are reflexively anti-vaccine: All nine justices are vaccinated, and they’ve spent much of the pandemic working remotely with limited in-person access to the Supreme Court building. Recently, too, the justices have refused to block a variety of vaccine mandates, including vaccine requirements for students at Indiana University and for health care workers in New York. 

But on the other hand, the Biden administration could still face significant skepticism from some of the justices since the vaccine requirements they’ve considered so far involve states and private entities — not the federal government. There’s likely a real question, too, in some of the justices’ minds about whether the executive branch has the authority to issue such sweeping mandates. Limiting federal agencies’ power to regulate is an issue that a few justices have appeared eager to tackle, and legal experts told me that the court’s conservatives might be sympathetic to arguments that the mandates amount to federal overreach, especially considering their treatment of Biden’s other pandemic policies and how the cases have fared in the lower courts so far.

“​​If you do the counting, the partisanship of the outcomes is disturbingly predictable,” said Wendy Parmet, a health law professor at Northeastern University. “You have basically all Democratic appointees upholding [the vaccine mandates]. And almost all of them are being struck down by Republican appointees.” The implications of these cases, she said, could extend far beyond this pandemic, too, with the potential to significantly limit the government’s ability to quickly respond to health care crises in the future.

The two requirements in front of the court on Friday were both rolled out by the Biden administration in early November, as part of a broader push to lift vaccination numbers. And the more sweeping requirement of the two came from the Department of Labor’s Occupational Safety and Health Administration (OSHA), which announced that it would require employers with 100 or more employees to verify that every worker is fully vaccinated or tested weekly for COVID-19. The other mandate came from the Centers for Medicare and Medicaid Services (CMS), and requires health care workers at facilities that receive Medicare and Medicaid funding to be fully vaccinated. According to Biden administration estimates, the OSHA mandate would affect 84 million workers and the CMS mandate would affect 17 million workers.

Almost as soon as the mandates were announced, though, a flurry of lawsuits were filed in federal courts across the country, and they’ve been ping-ponging around those courts ever since. Republican-appointed judges raised a number of objections in those cases, too, including claiming that CMS likely didn’t have a good enough reason for issuing the vaccine mandate for health care workers. That’s similar to the reasoning that sank many Trump-era policies in the courts, although other courts said that CMS had followed the rules.

But these weren’t just boring, jargony opinions about whether the Biden administration had crossed its t’s and dotted its i’s when it issued the mandates. Conservative federal judges also questioned the necessity of the vaccine mandates in their rulings, downplaying the severity of the pandemic and expressing skepticism about the science behind the mandate. “[I]t remains unclear that COVID-19 — however tragic and devastating the pandemic has been — poses the kind of grave danger that justifies the federal government trampling on sovereign state rights,” one of the lower-court judges wrote, echoing rhetoric that had appeared in an opinion from the Fifth Circuit Court of Appeals days earlier. 

And this kind of fiery, culture-war rhetoric could end up resonating with some Supreme Court justices. After all, this past summer, the justices threw out the Biden administration’s eviction moratorium, with the unsigned majority opinion stating that the Centers for Disease Control, which had issued the moratorium, had essentially gotten out over its skis. “The CDC has imposed a nationwide moratorium on evictions in reliance on a decades-old statute that authorizes it to implement measures like fumigation and pest extermination,” the justices wrote. “It strains credulity to believe that this statute grants the CDC the sweeping authority that it asserts.” 

The three liberal justices dissented from this opinion, but it’s not hard to imagine the conservative justices applying similar logic to the Biden administration’s vaccine mandates.

The Biden administration will argue that the vaccine mandate is urgently needed to protect countless Americans’ lives and health, but the conservative justices — like other Republican appointees in the lower courts — might not be convinced by that argument, even if it’s backed by experts. It wouldn’t be the first time that the justices sniffed at scientific analysis. Indeed, some have already signaled that they think the pandemic is no longer that big of an emergency. In a dissent from the court’s decision not to block a vaccine mandate in Maine, Justice Neil Gorsuch, joined by Justices Samuel Alito and Clarence Thomas, implied that the seriousness of the pandemic was diminishing as treatments and vaccines were developed — making it harder to justify government interventions like vaccine mandates. 

Thus far, Justices Amy Coney Barrett and Brett Kavanaugh have not sided with the other three conservative justices, instead opting to keep the high court out of challenges to state vaccination mandates, which has effectively left the mandates in place. That may seem surprising, given that as soon as Barrett joined the court in fall 2020, the court became very aggressive about overturning state restrictions on religious gatherings. But while Barrett and Kavanaugh might be more skeptical of the mandate for large employers, Parmet told me that striking down the vaccination requirement for health care workers could bring lots of other regulations into question. So it’s possible that Barrett and Kavanaugh might be drawn to a middle path, where they uphold the requirement for health care workers and overturn the requirement for employers.

How this showdown ends doesn’t matter for just the pandemic, though. From the beginning of Biden’s presidency, it’s been clear that the conservative-controlled Supreme Court poses a serious risk to his agenda. Now it could be poised to reject one or both of the pillars of Biden’s effort to control COVID-19 in the workplace — a decision that could have serious ramifications for him and his party during the midterms later this year. And more broadly, overturning one or both of the mandates would likely hurt the federal government’s ability to respond quickly to public health emergencies in the future, too. “It will fundamentally make it more difficult for the government to govern,” Parmet said.