(Reuters) - A federal appeals court on Tuesday heard arguments over whether to revive an Indiana law requiring healthcare providers to report complications from abortion to the state, which a lower court struck down as unconstitutionally vague after it was challenged by Planned Parenthood.

Judges Frank Easterbrook, Diane Wood and Amy St. Eve, of the 7th U.S. Circuit Court of Appeals, presided over the argument, with Thomas Fisher of the Office of the Attorney General of Indiana arguing for the state and Gavin Rose of the American Civil Liberties Union of Indiana arguing for Planned Parenthood.

The law, passed in 2018, lists 25 conditions that providers must report to the state if they arise from abortion, including immediate complications like incomplete abortion and other conditions like low blood sugar and anxiety. It would punish violations with up to 180 days in jail.

In its lawsuit, Planned Parenthood said the law did not give providers any guidance about when they would have to report one of those conditions as a complication arising from an abortion that a woman may have had in the past. The organization also argued that there was no medical basis to link many of the conditions to abortion, and that the real purpose of the law was simply to stigmatize abortion.

U.S. District Judge Richard Young in Indianapolis agreed that the law was unconstitutionally vague and enjoined it from taking effect, prompting the state to appeal.

Wood pressed Fisher to clarify the standard for reporting under the law. If a woman complained of anxiety at age 45, would that have to be reported if a doctor concluded that an abortion she had at age 23 contributed to the anxiety?

"That's exactly right," Fisher said. "That's exactly what the statute requires as long as it's a reasonable medical judgment."

St. Eve also asked how the law would work given disagreement in the medical community about the link between abortion and some of the conditions.

"Since even in the objective medical community there's disagreement, why wouldn't that just lend itself to arbitrary enforcement of this provision?" she asked.

Fisher said the focus was not on enforcement but on gathering information, prompting Wood to ask whether the true reason for the law was to discourage abortion. She said that providers, facing severe penalties, were likely to over-report and produce "junk data."

"It's going make abortions look as though they're much riskier than they are," she said.

Rose also faced skeptical questioning as he defended Planned Parenthood. Easterbrook noted that there was no precedent for holding the phrase "arising from" to be unconstitutionally vague, and that the phrase was common in the law.

"Are you asking us to hold a core phrase in American jurisprudence unconstitutional for the very first time?" he asked.

"Under the circumstances of this statute, yes," Rose said.

Rose emphasized that the statute could require providers to report conditions as abortion complications even though there was no medically supported link.

"No one would describe a bad transaction to a blood transfusion as arising from the abortion procedure," he said.

The case is Planned Parenthood of Indiana and Kentucky v. Marion County Prosecutor et al, No. 20-2407.

For Indiana: Thomas Fisher of the Office of the Attorney General of Indiana

For Planned Parenthood: Gavin Rose of the American Civil Liberties Union of Indiana