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.

Justice Clarence Thomas asked Solicitor General Elizabeth Prelogar if there is anyone who would have have a legal right to sue in this case -- which quickly emerged as the first major topic of the court's questioning of the federal government. The FDA has claimed the current plaintiffs do not have standing, with Prelogar suggesting at the hearing that their relationship to people who use mifepristone is too speculative and remote.

Prelogar said there may be an instance where a "competing drug manufacturer might sue and claim that FDA approval of a drug creates a competitive harm or injury or injury in that sense."

Chief Justice John Roberts asked if there is a number of adverse events or a number of patients who go to the emergency room in which the arguments would change. Facing such questions, Prelogar responded by reiterating her view that these possibilities appeared to be too theoretical and detached from specific decision-making and the history of patients who have used mifepristone.