A majority of the Supreme Court seemed inclined on Tuesday to reject a bid to sharply limit access to abortion pills.

During about 90 minutes of argument, most of the justices seemed doubtful that the plaintiffs, who do not prescribe abortion pills or regularly treat abortion patients, even had standing to bring the challenge. The justices, including several in the conservative majority, questioned whether the plaintiffs could show that they faced the moral harm they claimed to suffer from the availability of the pill, mifepristone.

The case centers on whether changes the Food and Drug Administration made in 2016 and 2021, which broadened access to the drug, would have to be rolled back.

Those changes made it possible for patients to obtain prescriptions for mifepristone by telemedicine and receive abortion pills in the mail, which has greatly increased the availability of medication abortion.

Several justices questioned the remedy the plaintiffs seek: to apply nationwide restrictions to the drug in a case that would have very broad implications because it would be the first time a court had second-guessed the F.D.A.’s regulatory authority.

“This case seems like a prime example of turning what could be a small lawsuit into a nationwide legislative assembly on an F.D.A. rule or any other federal government action,” said Justice Neil Gorsuch, an appointee of President Donald J. Trump.

Here are some takeaways:

The plaintiffs’ claims of being entitled to sue were met with great skepticism.

To have standing, plaintiffs must show they face concrete harm from the policy or action they are challenging in court. In this case, the plaintiffs, a group of anti-abortion doctors and organizations, say they face moral harm because patients who take abortion pills might seek treatment afterward at emergency departments in hospitals where some of those doctors work.

Solicitor General Elizabeth B. Prelogar, arguing for the government, said the plaintiffs did not “come within 100 miles of the kinds of circumstances this court has previously identified” as grounds for standing. She cited the fact that the doctors do not prescribe abortion pills and are not forced to treat women who take abortion pills. More crucially, she pointed to the fact that because serious complications from abortion pills are very rare, these doctors would not often encounter a woman who had experienced a serious complication requiring them to provide treatment.

The plaintiffs’ lawyer, Erin Hawley, countered by saying the doctors had treated abortion pill patients in emergency departments. She cited the written declarations in the case of Dr. Christina Francis and Dr. Ingrid Skop.

Justice Amy Coney Barrett questioned whether those doctors had provided examples of “actually participating in the abortion to end the life of the embryo or fetus.” She added, “I don’t read either Skop or Francis to say that they ever participated in that.”

The justices also questioned whether the anti-abortion organizations in the case have standing. Those organizations contend that they experience harm because in order to challenge the abortion pill, they have had to divert resources from other advocacy efforts.

Justice Clarence Thomas seemed skeptical of that claim, saying that having to prioritize how an organization spends its time and money would apply to “anyone who is aggressive or vigilant about bringing lawsuits. Just simply by using resources to advocate their position in court, you say now, causes an injury. That seems easy to manufacture.”

There was a lot of discussion about conscience protections.

Federal conscience protections allow doctors and other health care providers to opt out of providing care that they object to on moral or religious grounds. In many hospitals, doctors register their conscience objections in advance so they are never called upon to participate in care they object to.

Lawyers for the government and for a manufacturer of mifepristone, Danco Laboratories, said that if the anti-abortion doctors did encounter an abortion patient, they could easily invoke conscience protections and pass the case to another doctor who did not have moral objections. The plaintiffs are “individuals who do not use this product, do not prescribe this product and have a conscience right not to treat anyone who has taken this product,” said Jessica Ellsworth, a lawyer representing Danco.

Ms. Hawley said there were sometimes occasions in emergency departments where the plaintiffs would not have time to opt out, forcing them to “choose between helping a woman with a life-threatening condition and violating their conscience.”

Justice Ketanji Brown Jackson said there was “a mismatch” between what the anti-abortion doctors are claiming they have experienced and the remedy they are seeking. “The obvious common-sense remedy would be to provide them with an exemption, that they don’t have to participate in this procedure,” Justice Jackson said.

Noting that such a remedy already exists in the form of conscience protections, she said: “I guess, then, what they’re asking for in this lawsuit is more than that. They’re saying, ‘Because we object to having to be forced to participate in this procedure, we’re seeking an order preventing anyone from having access to these drugs at all. ”

Justice Barrett asked about the plaintiffs’ claim that the Emergency Medical Treatment and Labor Act, or EMTALA, which requires emergency departments in hospitals to treat patients with urgent medical issues, would override doctors’ conscience objections and force them to treat patients who have taken abortion pills anyway. Ms. Prelogar said that would not happen because EMTALA applies to hospitals, not individual doctors, so doctors with moral objections could opt out.

The case could affect the government’s role in regulating drugs — and possibly in regulating anything.

Many experts on regulatory policy and leaders in the pharmaceutical industry have said that if the court decides to undermine the scientific expertise of the F.D.A., it would deter companies from developing new medications and would ultimately hurt patients who would not have those medications available. They say it could also shake the regulatory authority of other government agencies.

Several justices asked about this issue. “Do you have concerns about judges parsing medical and scientific studies?” Justice Jackson asked Ms. Ellsworth, the lawyer for the manufacturer. Ms. Ellsworth said that was a concern, noting that two studies the plaintiffs had cited to show mifepristone was unsafe had been recently retracted.

“That is why FDA has many hundreds of pages of analysis in the record of what the scientific data showed,” Ms. Ellsworth said. “And courts are just not in a position to parse through and second-guess that.

A 19th-century anti-vice law made an appearance.

The Comstock Act, enacted in 1873, bars the mailing of drugs that can be used to terminate pregnancies.

Justices Alito and Thomas asked whether the act, which has not been used in decades and has been narrowed by the courts and Congress, applied, as the plaintiffs claim.

“The Comstock provisions don’t fall within F.D.A.’s lane,” said Ms. Prelogar, who said that the F.D.A.’s responsibility was to determine the safety and effectiveness of drugs and to regulate them. She also pointed out that the Justice Department issued an opinion that the Comstock Act applied only if the sender intended for the recipient of the materials to “use them unlawfully.”

Ms. Ellsworth warned of what might ensue should the court decide the act applied. “I think this court should think hard about the mischief it would invite if it allowed agencies to start taking action based on statutory responsibilities that Congress has assigned to other agencies,” she said.