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 Elena Kagan pressed Solicitor General Elizabeth Prelogar on the "arresting" statement from the government that this case marks the first time any court has restricted access to an FDA-approved drug.

"That is still to our knowledge the only time a court has done that," Prelogar responded.

"We have seen a disturbing trend of courts sometimes also overriding FDA's judgment to try to grant greater access to drugs and that overrides FDA expert judgment about what's necessary to ensure safe use," she continued. "And no matter which direction you come at it from we, on behalf of FDA, think that courts have no business making those judgments."

Solicitor General Elizabeth Prelogar suggested that the anti-abortion plaintiffs were seeking a sweeping ruling to reverse the FDA's approval of the abortion medication mifepristone because of their personal conscience views.

Prelogar was agreeing with Justice Ketanji Brown Jackson, who raised that idea as she called it a "mismatch" between the issues brought by the plaintiffs and what they are asking the court.

"The obvious common sense remedy would be to provide them with an exemption that they do not have to participate in this procedure and you say federal law already gives them that," Jackson said.

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.