A state grand jury in Louisiana has indicted a New York doctor for providing abortion pills to a Louisiana resident. The case appears to be the first time criminal charges have been filed against an abortion provider for sending pills into a state with an abortion ban.

The charges mark a new chapter in an escalating showdown between states that ban abortion and those that want to protect and expand access to it. It is challenging one of the foremost strategies used by states that support abortion rights: shield laws intended to provide legal protection to doctors who prescribe and send abortion pills to states with bans.

The charges were brought against Dr. Margaret Carpenter, who was operating under New York’s telemedicine abortion shield law, which stipulates that New York authorities will not cooperate with prosecutions or other legal actions filed against New York abortion providers by other states.

Telemedicine abortion shield laws, which have been adopted by eight states so far, have become a significant avenue for providing access to abortion for women in states with bans without requiring them to leave their state. Doctors, nurse practitioners and other health care providers in states with shield laws have been sending more than 10,000 abortion pills per month to states with abortion bans or restrictions.

Legal experts said the case ratchets up the legal wars over abortion and will almost certainly end up in federal court and possibly the Supreme Court. It is expected to become a major test of whether states can apply criminal laws to people acting outside their borders.

Since the Supreme Court’s 2022 decision in Dobbs v. Jackson Women’s Health Organization overturning the national right to abortion, the United States has been divided between states that restrict abortion and states that protect abortion.

“There’s just been a sense that if you were in a blue state, you’re shielded from the consequences of Dobbs,” said Mary Ziegler, a law professor and abortion expert at the University of California, Davis. “Prosecutions like this undermine that assumption, and we don’t know exactly how, or how much, but you can’t take that for granted.”

Federal courts will have to sort out “where the line will be drawn and even which precedents the courts will be willing to overrule,” she said. “It’s not clear what will happen.”

The Louisiana indictment, by a grand jury in West Baton Rouge Parish, follows what is believed to be the first civil suit filed against an abortion provider in a shield-law state. That case was filed in December by the Texas attorney general, Ken Paxton, also against Dr. Carpenter, for prescribing and sending pills to a woman in Texas.

On Friday, Tony Clayton, the district attorney who oversees West Baton Rouge, said in an interview, “I just don’t know under what theory could a doctor be thinking that you should ship your pills to Louisiana to abort our citizens’ babies.”

He added: “The pill may be legal in New York. It’s not legal in Louisiana.”

In response to the charges, Gov. Kathy Hochul of New York said in a video posted on X, “I will never, under any circumstances, turn this doctor over to the state of Louisiana under any extradition request.” She pledged “to do everything I can to protect this doctor and allow her to continue the work that she’s doing that is so essential.”

The use of abortion medication has grown significantly in recent years. Medication abortions now account for nearly two-thirds of pregnancy terminations in the United States. The method is typically used through 12 weeks of pregnancy and involves two drugs — mifepristone, which stops a pregnancy from developing, followed a day or two later by misoprostol, which causes contractions similar to a miscarriage.

In 2021, the Food and Drug Administration lifted a rule requiring patients to obtain mifepristone in person, allowing the medication to be sent through the mail.

The ability to mail the medications, bolstered by shield laws, has made it much more difficult for states with bans to prevent their residents from getting access to abortion. The actions filed against Dr. Carpenter in Texas and Louisiana are part of a campaign to limit that access.

Abortion opponents are also pressing the Trump administration to revive a 151-year-old federal anti-vice law known as the Comstock Act and use it to try to prevent the mailing of abortion pills.

In the Louisiana case, the grand jury indicted Dr. Carpenter and her medical practice for “criminal abortion by means of abortion-inducing drugs.”

Dr. Carpenter, of New Paltz, N.Y., did not comment on the case on Friday, and efforts to reach lawyers representing her were unsuccessful.

The court documents, which include few details, indicate that the case involved a girl who was under 18 whose mother ordered abortion pills and gave them to her in April 2024. The mother was also charged with violating the state’s abortion ban.

Mr. Clayton, the West Baton Rouge district attorney, said the authorities became aware of the case after a police officer responded to a 911 call placed by the teenager.

“The officer at the time thought he was dealing with a child who was having a miscarriage,” Mr. Clayton said. After the police took the teenager to a hospital, the authorities learned that she had taken abortion medication and the investigation became criminal, he said.

Mr. Clayton, who declined to disclose the age or other details about the girl, said that “the evidence will show that the child had planned a reveal party” and did not want an abortion. He said that charges would not be filed against the girl.

Police records show that the mother, whose name The New York Times is not disclosing to protect the identity of her daughter, was arrested and released on bond. Attempts to reach her on Friday were unsuccessful.

“The allegations in this case have nothing to do with reproductive health care,” said Liz Murrill, the state attorney general. “This is about coercion. This is about forcing somebody to have an abortion who didn’t want one.”

The attorney general of New York, Letitia James, said in a statement, “This cowardly attempt out of Louisiana to weaponize the law against out-of-state providers is unjust and un-American.”

She added: “Medication abortion is safe, effective and necessary, and New York will ensure that it remains available to all Americans who need it.”

Dr. Carpenter is a specialist in reproductive health and a co-founder of the Abortion Coalition for Telemedicine, an organization that advocates access to telehealth abortion in all 50 states.

“Shield laws across the country enable licensed health care professionals to successfully deliver reproductive health care to patients in under-resourced areas nationwide,” the coalition said in a statement on Friday, adding, “This state-sponsored effort to prosecute a doctor providing safe and effective care should alarm everyone.”

Anti-abortion activists praised the Louisiana charges.

“This case exposes how mail-order abortion drugs are fueling an epidemic of coercion, a new form of domestic violence against mothers and their babies,” Katie Daniel, director of legal affairs for SBA Pro-Life America, said in a statement. The statement commended Louisiana for tightening laws against abortion medication and said, “In blue states, pro-abortion politicians are doing the polar opposite, shielding abortionists.”

In the Texas lawsuit, Dr. Carpenter was accused of providing abortion pills to a 20-year-old woman in July. The suit said the woman later asked the “biological father of her unborn child” to take her to the emergency room because of “severe bleeding,” and he learned at that time that she was nine weeks pregnant.

Mr. Paxton said that by filing the Texas lawsuit, he was seeking to have the court stop Dr. Carpenter from continuing to provide abortion medication to patients in Texas, and to apply Texas’ ban on abortion to her. The ban carries a penalty of at least $100,000 for each violation.

Kirsten Noyes contributed research.