A federal judge in Texas is set to rule on a lawsuit that seeks to restrict access to one of the two drugs typically used to induce a medicated abortion. The decision could impact 40 million women nationwide, making it the most consequential legal ruling since the Supreme Court overturned Roe v. Wade.

More than half of all abortions in the U.S. use mifepristone. 

Dr. Kristyn Brandi, an OB-GYN in New Jersey, said the ruling could mean drastic changes for patients, adding that a ban would be “devastating.” 

“A lot of people rely on this medication,” she told CBS News. “It is something that has been the standard of care for over 20 years.”

A lawsuit filed by the Alliance for Hippocratic medicine, an anti-abortion organization, seeks to reverse the Food and Drug Administration’s approval of the drug and remove it from the market. The lawsuit alleges there have not been sufficient studies into the safety of mifepristone. 

Julie Marie Blake, senior counsel for the Alliance Defending Freedom, a conservative Christian legal advocacy group, said the organization is “confident that when any court looks at the law and looks at the science, it will realize that the FDA has completely failed its responsibility to protect women and girls.”

The FDA said it does not comment on pending litigation, but physicians’ groups, including the American College of Obstetricians and Gynecologists, said mifepristone is “safe and effective.”

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Mifepristone can be ordered online with a prescription, even in states where surgical abortions are restricted. The drug is also used to treat miscarriages.

The decision in the lawsuit is now in the hands of a Trump-appointed federal judge.

Meghan Boone, an associate professor at Wake Forest University School of Law, said that “if there is a nationwide injunction, then the drug used for medication abortions will be off the market in all 50 states at least, and during, the period where the injunction is in force.”

Boone said the outcome of the case may also undermine the FDA approval process, setting a damaging precedent.

Brandi said that, even if mifepristone is banned, patients would still be able to get a medication abortion by using misoprostol, the other drug in the two-drug combination.

“It’s a little bit less effective,” Brandi said. “There may be higher risk of side effects or people needing additional care.”