Attorney Erin Hawley, representing the anti-abortion Alliance for Hippocratic Medicine that is challenging mifepristone, has begun her presentation to the justices.

Hawley is echoing the alliance's attacks on the drug's use and regulation by the FDA, contending that it creates harm to women and burdens doctors who must then care for such patients who use mifepristone.

Hawley also invoked an "intolerable" choice that is created by the widespread use of mifepristone -- if an anti-abortion doctor must consider treating abortion patients in an emergency situation or not.

-ABC News' Adam Carlson

Jessica Ellsworth, the attorney for Danco Labs, was asked by Justice Ketanji Brown Jackson if she was concerned about the prospect of judges parsing medical and scientific studies without specialized knowledge.

"I think we have significant concerns about that," Ellsworth said, noting the pharmaceutical industry submitted briefs to the court expressing that worry.

She went on to state that U.S. District Judge Matthew Kacsmaryk, who initially ruled to suspend mifepristone's approval, relied on studies that "were not in the administrative record" and never would have been.

"They have since been retracted for lack of scientific rigor and misleading presentations of data," she said.

Sage Publishing said it issued the retractions from the journal Health Services Research and Managerial Epidemiology because of methodology issues and conflicts of interest, ABC News previously reported.

Justice Samuel Alito asked Jessica Ellsworth, the attorney representing Danco Laboratories, if she thinks the FDA should have continued requiring prescribers to report non-fatal complications, known as “adverse events" of mifepristone.

Ellsworth argued the FDA made that decision after 15 years of data that established mifepristone was safe. She also rejected Alito's question asking if the FDA was "infallible".

Justice Kentanji Brown Jackson asked if the defendants had concerns about judges "parsing medical and scientific studies" and Ellsworth said there were concerns.

Jessica Ellsworth, who is representing the manufacturer of Mifeprex (the brand name of mifepristone), similarly criticized the plaintiff's claim of injury and their interpretation of the law.

She said the respondent's view is "so inflexible it would upend not only Mifeprex but virtually every drug approval and [risk and mitigation] modification the FDA has made for decades."

The lead plaintiff, the Alliance for Hippocratic Medicine, had initially challenged the FDA’s approval of mifepristone.

But the matter before the high court now is more narrow -- whether the FDA's subsequent regulatory decisions about the drug, in 2016 and 2021, were sound.

In court filings, the Alliance Defending Freedom, a Christian conservative legal advocacy representing the plaintiffs, has claimed mifepristone is not safe and that the FDA didn't study it closely enough before it was approved.

The group also argued that the FDA’s decisions in 2016, lowering the recommended dosage and extending the use from seven weeks through 10 weeks of pregnancy, and in 2021, which permanently lifted the restriction on requiring abortion pills to be dispensed in-person, were unsound.

In January 2022, the FDA went further by allowing retail pharmacies to provide the drug too, either by mail or in person, so long as they meet certain requirements, which the plaintiffs claim violate federal laws that prohibit the distribution of chemical abortion drugs by mail.

The FDA rejects the claims, arguing that mifepristone is safe when used as indicated and directed, and that the pill went through a thorough and comprehensive review before being approved.