A coalition of state attorneys general is suing the Food and Drug Administration, accusing the agency of excessively regulating the abortion pill mifepristone.

Mifepristone was approved more than 20 years ago to induce first-trimester abortions in combination with a second drug, misoprostol. The lawsuit, filed in federal court in Washington state by a dozen Democratic state attorneys general, asks the FDA to lift additional layers of regulation above and beyond those for typical prescription drugs.

It accuses the FDA "singling out mifepristone...for a unique set of restrictions," and asks the court to declare the drug to be safe and effective, and invalidate the additional regulation, known as a Risk Evaluation and Mitigation Strategy or REMS.

In an interview with NPR, Washington state Attorney General Bob Ferguson, who co-led the suit, noted that the REMS has been applied only to a few dozen high-risk prescription drugs — such as fentanyl and other opioids.

Regarding mifepristone, "what we're asking the court to do is remove those restrictions and make access to this important medication more available to women across the country," Ferguson says.

Since it was approved in 2000, mifepristone has been the subject of heated political debate surrounding abortion. For years, reproductive rights advocates and major medical groups have pushed for removing the REMS. In recent years, the Biden administration has loosened some requirements, allowing the drug to be delivered by mail and making it easier for major pharmacies to eventually dispense the drug. But prescribers are still subject to additional rules such as special certification requirements.

The lawsuit comes as a federal judge in a separate case in Texas is considering whether to overturn the FDA's approval of the abortion drug, setting up the possibility of conflicting rulings by different federal judges.

"So you'll have two federal judges potentially looking at the future of mifepristone, whether to expand access to it or eliminate access altogether," Ferguson says.

He says the question of how to regulate mifepristone could end up before the U.S. Supreme Court.

In a statement to NPR, Erik Baptist, senior counsel with Alliance Defending Freedom, the anti-abortion legal group leading the mifepristone challenge in Texas, noted that a group of Democratic attorneys general filed a brief in that case supporting the FDA's approval of the drug.

"We find it highly ironic that the same attorneys general who filed an amicus brief in our case two weeks ago arguing that the FDA's judgments must not be second-guessed have now filed a lawsuit in a different court arguing just the exact opposite," Baptist says.

Major medical groups including the American College of Obstetricians and Gynecologists and the American Medical Association filed an amicus brief in the Texas case calling mifepristone "thoroughly studied" and "conclusively safe."

An FDA official says the agency does not comment on ongoing litigation.