(AMARILLO, Texas) -- A ruling from a federal judge in Texas -- that may come as soon as Friday -- could potentially block use of an abortion medication across the United States.
A lawsuit is asking that the U.S. Food and Drug Administration's approval of mifepristone be revoked and that the drug be pulled from the market.
If the judge rules in favor of the plaintiffs, there would be a nationwide injunction on mifepristone, affecting even states where the procedure is legal. Another drug used in combination with mifepristone for abortions, called misoprostol, would still be available, but it's not approved by the FDA to be used for abortions on its own.
Abortion rights groups fear the decision will restrict abortion even more so than the Supreme Court did when it overturned Roe v. Wade last summer.
"This would be devastating," Kirsten Moore, director of the EMAA Project, which works to expand access to medication abortion, told ABC News of the ruling's impact. "This would be taking an FDA approved drug off the market for no public health reason."
What is mifepristone?
Mifepristone is a drug typically used in combination with another drug to induce an abortion or to help manage an early miscarriage.
The medication works by blocking the hormone progesterone, which the body needs to continue a pregnancy.
This causes the uterine lining to stop thickening and to break down, detaching the embryo. The second drug, misoprostol, taken 24 to 48 hours later, causes the uterus to contract and dilates the cervix, which will expel the embryo.
Mifepristone was authorized by the U.S. Food and Drug Administration in 2000. In the U.S., the drugs are approved up to 10 weeks' gestation, although the World Health Organization says they can be taken up until the 12-week mark.
Medication abortion now accounts for more than half of all abortion in the U.S., according to the Guttmacher Institute.
In December 2021, the FDA announced it permanently lifted its restriction that abortion pills had to be dispensed in-person. Last month, it went further by allowing retail pharmacies to provide the drug too, either by mail or in person, so long as they meet certain requirements.
What is the lawsuit?
In November 2022, a lawsuit was filed by Alliance Defending Freedom, a Christian conservative legal advocacy group working to outlaw abortion, on behalf of four anti-abortion medical groups and four physicians, who claim they have used the drug to treat patients.
The FDA says mifepristone is safe and effective when used as directed and no new safety concerns have arisen in the more than two decades since it was approved.
ADF claims the federal health agency "chose politics over science and approved chemical abortion drugs for use in the United States," according to the lawsuit.
Julie Marie Blake, senior counsel at ADF, told ABC News on Wednesday that the lawsuit shouldn't impact miscarriage care and that mifepristone could still be prescribed to treat Cushing's Syndrome, an endocrine disorder.
But if the judge agrees, it could no longer be prescribed to induce an abortion.
"The FDA has completely failed to protect America's women and girls when it comes to chemical abortion drugs," Blake told ABC News. "Any court -- to look at the law and to look at the science -- should agree that the FDA has failed in its responsibility to protect women and girls, and that it's time to remove these drugs from the market -- or at a minimum, to put back important safeguards on their use."
The 113-page lawsuit also argues the FDA exceeded its authority and ignored "intense side effects" because it was under pressure to approve the drug under then-U.S. President Bill Clinton.
"This case is unusual, because it's challenging a drug that's been on the market for over 20 years and extremely safe," Rabia Muqaddam, a senior staff attorney at the Center for Reproductive Rights, told ABC News. "The evidence that they suggest shows medication abortion is unsafe, has been repeatedly rejected by the FDA. And despite the claims having very little legal merit, and the plaintiffs not really having any injury, this case, has the potential to really undermine the remaining access to abortion that exists."
What would the case decide?
The case was filed in Amarillo, Texas -- a state where abortion is already severely limited -- and assigned to U.S. District Court Judge Matthew Kacsmaryk, who was nominated by former President Donald Trump.
Kacsmaryk is known for his conservative stance on issues and, last year, he issued a decision on Title X, a federal grant program that provides confidential family planning and preventive health services.
He ruled that teenagers can't access birth control without their parents' permission under the program because it "violates the constitutional right of parents to direct the upbringing of their children."
If Kacsmaryk rules in favor of ADF, mifepristone would, at least temporarily, be taken off the market and all states where abortion is legal would only be able to offer in-clinic procedures.
This means patients will not be able to access telehealth services to get abortion pills and clinics already experience a surge of patients from states where abortion is illegal could be even more inundated.
"It's going to impose a really significant burden and cause significant congestion at the clinics that still remain," Muqaddam said. "We're seeing long wait times, so many patients trying to travel to access state to seek care. It's been a huge challenge. It's going to cause a pretty immediate and extreme constriction and the accessibility of abortion."
The decision could come as early as Feb. 10, which is the deadline both sides in the case have to file briefs.
ABC News' Anne Flaherty contributed to this report.