Pennsylvania’s highest court ruled Friday that mothers who use illegal drugs while pregnant cannot be considered perpetrators of child abuse against their newly born children under the state’s child protection law.

The Supreme Court’s main opinion said the law’s definition of a child does not include fetuses or unborn children, and victims must be children under the Child Protective Services Law.

Two justices who dissented said what should matter is when the injury shows itself, and that can be after the child is born.

The case involves a girl who spent 19 days in Williamsport Hospital last year after she was born, being treated for drug dependence that caused severe withdrawal symptoms. Her mother relapsed into drug use after getting out of jail, and two weeks before the girl was born in January 2017 the mother tested positive for opiates, marijuana and benzodiazepines, Donohue wrote.

While her daughter was hospitalized, Donohue wrote, the mother did not check in on her or stay with her. Clinton County Children and Youth Services was granted protective custody. In May 2017, the county judge determined the law did not provide for a finding of abuse for what occurred before the girl was born.

The Clinton County child welfare agency argued that a finding of child abuse would help protect other children if the mother were to become pregnant again.

The mother’s lawyer, David S. Cohen, called the decision a victory for public health and the rights of women and children.

“There are many states that have decided by statute to label this type of behavior child abuse, but the majority do not,” Cohen said Friday. “We think that’s the right way to approach this, because this is a health issue and the worst thing you can do with a health issue is punish people. It drives people from treatment and it results in worse outcomes for everyone.”

The case was not a criminal matter, and Pennsylvania law already makes clear that mothers cannot be prosecuted for harming their fetuses. That’s because the state has traditionally held to the “born-alive rule,” a centuries-old legal precept that says a person isn’t a person until birth and isn’t entitled to general legal protections before then.

Northampton County may have one of the few instances — if not the only — in which a woman was successfully prosecuted for potentially harming her fetus by using drugs during pregnancy. In 2000, Toni Hill Rice of Bethlehem was convicted of child endangerment for abusing heroin while 7 months pregnant, serving 42 days in jail for it.

The National Conference of State Legislatures said the question of how to handle the exposure of unborn children to illegal drugs has been a challenge for many states, raising issues of how to keep families together and cope with the strain on the foster care system.

Friday’s decision in the state’s child protection law overturns the Superior Court, which ruled a county judge erred in deciding the mother’s drug use did not qualify as child abuse.

Superior Court Judge Geoffrey Moulton wrote a year ago that a mother’s substance abuse while pregnant “may constitute child abuse” if authorities can prove she “intentionally, knowingly, or recklessly caused, or created a reasonable likelihood of, bodily injury to a child after birth.” Moulton wrote the word “after” in boldface.

A phone message left for the lawyer for Clinton County Children and Youth Services was not returned.

If the woman had been deemed a perpetrator, that would have put her on a lifetime registry and would have affected her employment and ability to volunteer around children, Cohen said.

Cohen said his client does not have custody of her daughter.