In 1937, a drugmaker called S.E. Massengill Co. came up with what seemed like an improvement on an effective medicine for sore throats: a liquid formulation that tasted like raspberry.

The only problem: The new formulation of the drug, called sulfanilamide, used diethylene glycol, which is essentially poison. More than 100 people, many of them children, died after taking it.

The company didn’t know that diethylene glycol would be so dangerous, but it hadn’t been required to run toxicity studies before releasing a new product, and so it hadn’t done so, according to a US Food and Drug Administration account of the disaster.

The deaths led Congress the next year to pass the Federal Food, Drug and Cosmetic Act, which empowered the FDA to require drugs to be proven safe before they can be marketed. In 1962, Congress further expanded the FDA’s authority after the drug thalidomide was shown to cause severe birth defects — this time, to require that drugs be proven effective.

That dual mandate, in place for more than 60 years, has created a trusted drug approval process that could be upended by a case about the medication abortion drug mifepristone that’s being argued Tuesday in front of the US Supreme Court, according to doctors, former FDA commissioners, legal scholars, and pharmaceutical industry executives and investors.

“If the court ends up … ruling in any way in favor of the plaintiffs, it says that basically, anybody who may be ideologically opposed to medication approved by the FDA could try to go to court and overrule the scientific determination of the experts,” said Dr. Daniel Grossman, a professor at the University of California San Francisco and director of the university’s Advancing New Standards in Reproductive Health program.

The case at hand Tuesday focuses on mifepristone, one of two medicines in a regimen used for medication abortion — which accounted for 63% of abortions in the US in 2023, according to data from the Guttmacher Institute, a research and policy organization focused on sexual and reproductive health.

Last year, a district court judge in Texas agreed with the plaintiffs, a group of doctors opposed to abortion, that the FDA inappropriately approved mifepristone in 2000 and expanded how it could be used starting in 2016.

That decision would have removed mifepristone from the market, but the ruling was stayed as an appeals process began; the US 5th Circuit Court of Appeals found that the 2000 approval was too long ago to be overturned but agreed with the challenges to the expansions to the approval that began in 2016.

If the Supreme Court agrees with the appeals court, the approval of mifepristone could be reset to where it stood before 2016, limiting telehealth access to medication abortion and reimplementing other restrictions.

“That would be a significant change and restriction on access,” Grossman said.

But the prospects of a broader undermining of the FDA’s authority, he and others argue, is also on the line.

In addition to opening up any drug to challenges on ideological grounds, weakening the FDA’s authority could enable challenges from drug companies trying to remove a competitor’s product or to reverse the agency’s judgment about their own rejection, a group of former FDA commissioners wrote in a friend-of-the-court legal brief.

“This new paradigm would take a significant toll on public health,” they wrote.

The pharmaceutical industry and its investors also warned that a shakier regulatory system could lead to less investment in developing new medicines.

“Biopharmaceutical research and development is expensive, time consuming, and risky,” the Pharmaceutical Research and Manufacturers of America, or PhRMA, wrote in a brief. “Nevertheless, drug developers invest in new medicines because, if their investments succeed, FDA’s rigorous drug approvals and subsequent regulatory actions are sturdy enough to facilitate reliable returns.

“If endorsed by this Court,” PhRMA continued, “the Fifth Circuit’s attenuated standing analysis threatens to subject every drug approval and later action to a substantial risk of litigation, reducing revenues that drive investment and thereby diminishing the incentives to innovate in the first place.”

A separate brief from pharmaceutical companies, executives and investors warned of a “seismic shift in the clinical development, drug approval, and post-approval processes” if the Supreme Court allows the appeals court’s decision to stand.

“This additional uncertainty would make the already high degree of risk in these investments intolerable,” they wrote. “And without necessary investment, drug development would freeze, stifling innovation and limiting treatment options for patients.”

Of course, if the Supreme Court upholds the appeals court decision, the most immediate impact would be to mifepristone itself.

“That likely means they will put the original REMS” — a set of restrictions on how mifepristone can be used — “back into effect almost immediately,” I. Glenn Cohen, a professor at Harvard Law School who was among the food and drug law scholars who filed a friend-of-the-court brief, wrote in an email to CNN. “That will make mifepristone, and thus abortion, much harder to get since the 2016 and 2021 alterations significantly improved access.”

GenBioPro, which manufactures the generic version of mifepristone, said in its own friend-of-the-court brief that the company wouldn’t be able to sell the drug until it made “significant changes to its product and marketing practices that would be necessary to comply with the pre-2016 conditions and obtain FDA approval of those changes.”

“Across all of GenBioPro’s current customers and partners, the Fifth Circuit’s opinion creates a cloud of uncertainty over the legal status of existing inventory, especially inventory in the hands of distributors, dispensers, and patients,” the company said. “The utterly unprecedented nature of court-ordered changes to an approved drug label and products that are already in the stream of commerce threatens confusion and turmoil for all entities that purchase, distribute, prescribe, and use mifepristone.”

Cohen said that he expected the court to “throw out the case” because the plaintiffs lack standing to challenge the FDA’s decisions to expand access but that if the court instead upholds the appeals court decision, the FDA could seek to essentially redo the process of broadening access to the medicine. But, he said, it could be an uphill battle, and the agency’s willingness to do so could depend on the outcome of the US presidential election.

“It is both my hope and my ‘bet’ that the court doesn’t uphold the 5th Circuit on the standing argument,” Cohen wrote. “But I have learned the Supreme Court is hard to predict much of the time.”