HARTFORD, Conn. — When a 17-year-old Connecticut girl refused medical treatment for cancer and her mother agreed with her decision, state officials took custody of her and forced her to undergo what they called life-saving chemotherapy.

The Connecticut Supreme Court will review that series of events under an emergency appeal filed by lawyers for the girl and her mother, taking up an issue decided by several other states – whether some minors are mature enough to make decisions about their own bodies.

The high court is set to hear arguments Thursday in the case of the girl known in court documents only as Cassandra C., who will turn 18 in September. She was diagnosed with Hodgkin lymphoma last September, according to court documents.

Assistant Public Defender Joshua Michtom, who is representing Cassandra, said the case marks the first time the state Supreme Court will consider the “mature minor doctrine” recognized by several other states. The doctrine generally allows court hearings for minors 16 and 17 years old to prove that they are mature enough to make medical decisions for themselves.

“Give us the chance to prove that she has the maturity to do this,” Michtom said. “One has a right to bodily integrity. It doesn’t matter if it’s harmful. An adult’s right to refuse care is without limitation, provided they’re not incompetent.”

Cassandra is now confined to a room at Connecticut Children’s Medical Center in Hartford, with a hospital staffer posted at the door so she can’t leave, according to a brief filed by Michtom and Michael Taylor, an attorney for Cassandra’s mother, Jackie Fortin of Windsor Locks.

It’s not completely clear why Cassandra and her mother oppose chemotherapy, which doctors at the children’s medical center say would give Cassandra an 85 percent chance of survival, according to court documents. Without treatment, the doctors said there was a near certainty of death within two years.

Fortin did not return telephone and email messages from The Associated Press.

“She has always – even years ago – said that if ever she had cancer … she would not put poison into her body,” Fortin told WVIT-TV in a recent interview.

Michtom said the daughter and mother’s objection to treatment does not involve religion.

After Cassandra was diagnosed with high-risk Hodgkin lymphoma, she and her mother missed several appointments, prompting doctors at the hospital to notify the state Department of Children and Families, court documents say.

DCF investigated and a trial court granted the agency temporary custody of Cassandra. Lawyers for Cassandra and her mother then sought an injunction prohibiting medical treatment but were unsuccessful. The teen underwent two days of treatment in November but ran away for a week, court documents say.

Treatment on Cassandra resumed Dec. 17, with surgery to install a port in her chest that would be used to administer chemotherapy chemicals. Chemotherapy began the next day and continues, court documents say.

DCF officials defended their treatment of Cassandra.

“When experts, such as the several physicians involved in this case, tell us with certainty that a child will die as a result of leaving a decision up to a parent, then the department has a responsibility to take action,” they said in a statement.

The American Civil Liberties Union of Connecticut filed an amicus brief in the case, supporting the mature minor doctrine and calling for a hearing on whether Cassandra is mature enough to make medical decisions.

The ACLU says six states – Illinois, Maine, Tennessee, West Virginia, Michigan and Massachusetts – and Washington, D.C., have held or suggested that mature minors, like other competent people, have the right to consent to or forego medical treatment. Texas is the only state to reject the mature minor doctrine, the ACLU said.

“The appeal … involves a grave threat to one of our most basic civil liberties: the right to bodily integrity,” the ACLU’s brief said.