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."

With Jessica Ellsworth, representing mifepristone manufacturer Danco Labs, now speaking, Justice Clarence Thomas pressed her on the the 19th-century Comstock Act and why that legislation doesn't bar the use-by-mail of the abortion pill.

Ellsworth responded that Comstock has long not been enforced and that she believes this legal challenge is not an opportunity for the justices to "opine" on Comstock's reach.

The federal government previously said in Tuesday's hearing that they do not believe Comstock's requirements are within the FDA's purview as it regulates drugs.

Ellsworth seemed to echo that during her own presentation and questioning, warning that the justices "should think hard about the mischief" that could be created by requiring FDA regulatory approval to be restricted by provisions beyond safety.

-ABC News' Adam Carlson

Three women are participating in Tuesday's arguments.

Elizabeth Prelogar, the solicitor general at the Department of Justice, is arguing on behalf of the federal government.

Jessica Ellsworth is representing Danco Labs, the manufacturer of mifepristone.

Erin M. Hawley is counsel speaking for the Alliance for Hippocratic Medicine, a group of anti-abortion medical organizations that brought the challenge against the FDA and mifepristone.

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.