A New Jersey woman's use of methadone during pregnancy to treat a prescription drug addiction did not violate abuse and negligence laws, though her baby suffered from methadone withdrawal upon birth, the state Supreme Court ruled Monday.

In a 6-0 decision, the court reversed an Appellate Division ruling that the mother was negligent and abusive because her methadone use caused her child's suffering, which included tremors, fever, and trouble sleeping.

The high court said the previous ruling did not consider whether the woman "exercised a 'minimum degree of care' or 'unreasonably' inflicted harm on her newborn."

"A woman who becomes addicted to lawfully prescribed medication and then learns she is pregnant is confronted with a choice - either to seek treatment that will improve the outcome for her newborn or to continue on the path of her addiction," Justice Barry T. Albin wrote for the Supreme Court.

The lower court's reasoning "creates a perverse disincentive for a pregnant woman to seek medical help and enter a bona fide detoxification treatment program that will address her and her baby's health needs," he wrote.

The woman's attorney, Clara S. Licata, said: "We think it's the correct decision that supports a pregnant woman's right not just to have methadone treatment but to have medical treatment while pregnant even if it would have an effect on a newborn child."

Lynn M. Paltrow, executive director of National Advocates for Pregnant Women, which filed a brief in support of the woman, said the opinion was "an incredibly important decision that recognizes that methadone treatment for pregnant women is health care, not harm."

The Attorney General's Office referred comment to the Division of Child Protection and Permanency, which didn't respond to requests for comment.

The case, Division of Child Protection and Permanency v. Y.N., arose after the woman, identified in court documents as Y.N. or Yvonne, visited a hospital in September 2010 to seek treatment for an unrelated injury and learned she was four months pregnant.

Before learning she was pregnant, Yvonne had become dependent on Percocet, which she began using after being injured in a car accident months earlier.

Hospital staff told Yvonne she could lose her baby if she suddenly stopped taking the drug.

On the advice of medical professionals, she enrolled in a methadone maintenance treatment program in January 2011.

Her baby, referred to as Paul in court documents, was born in February that year and was hospitalized for seven weeks.

The Division of Youth and Family Services, now known as the Division of Child Protection and Permanency, filed a complaint against Yvonne alleging abuse and neglect.

The complaint, which sought care, custody and supervision of Paul, cited his mother's past drug abuse, her refusal to take a March 2011 drug test while in methadone treatment, allegations of domestic violence involving Yvonne and her child's father, and Paul's withdrawal.

A family court sided with the state but let Yvonne retain custody of her child under the state's supervision. An Appellate Division panel affirmed the court's abuse and neglect finding, and Yvonne appealed to the Supreme Court.

The state argued that Yvonne's intentions did not matter, because her child suffered actual harm.

But the high court said that to prove negligence and abuse violations of New Jersey's child-welfare laws, the state needed to prove that "at a minimum, a parent acted with gross negligence or recklessness."

"Sometimes a parent may cause injury to a child to protect that child from a greater harm. Under those circumstances, the parent may be acting reasonably," Albin wrote.

The law "requires more than a mere showing of harm to a child," Albin wrote.

"We hold that absent exceptional circumstances, a finding of abuse or neglect cannot be sustained based solely on a newborn's enduring methadone withdrawal following a mother's timely participation in a bona fide treatment program prescribed by a licensed health care professional to whom she has made full disclosure," he added.

The court remanded the case to the Appellate Division to decide whether other evidence, such as "the timeliness of Yvonne's seeking drug treatment," supported an abuse or neglect finding.