The court said judges must interview the minors and determine whether they are mature before deciding what is in their ''best interest.''
Richard A. Simons, who represents the Lenox teenager, said the ruling means minors who can convince a judge they are making a rational, intelligent choice to refuse medical treatment may see their wishes prevail over the objections of their parents and the state.
''The court is indicating'' that judges ''may consider the maturity of the child to make informed choices,'' said Simons, a Pittsfield attorney. ''And when that child expresses their preference and expresses their religious conviction, that's what's significant - rather than just saying a minor has no say in controlling his or her medical decisions.''
At issue in the case were the wishes of Alexis Demos, a 17-year-old Lenox girl who was seriously injured in a Jan. 26 snowboarding accident. As part of the medical treatment at the Berkshire Medical Center for her lacerated spleen, doctors said she could possibly need a life-saving blood transfusion if the spleen started to bleed.
Demos and her parents objected on religious grounds because as Jehovah's Witnesses they believe a blood transfusion would violate a biblical prohibition on ''eating blood.''
The hospital then asked Berkshire Superior Court Judge Judd Carhart to step in and permit doctors to administer the transfusion if needed, citing the state's interest in preventing an avoidable death of a child. Carhart, after hearing from Simons and the hospital, agreed with the hospital and ordered the transfusion if needed.
The Demoses appealed, and the court ruled yesterday even though Demos is no longer in immediate medical danger. The Appeals Court decided to rule in this case because of the scarcity of appellate cases in the area of a minors' rights to control medical intervention.
The court said that since a 1991 ruling by the Supreme Judicial Court, a competent adult clearly can refuse live-saving treatment. ''The law is well-settled ... that a competent adult may refuse medical treatment even if the treatment is necessary to save her life,'' Appeals Court Judge Elizabeth Porada wrote for the court.
The court said it has also been clear since 1991, in a separate SJC ruling, that judges can order life-saving treatment for minors when a parent refuses to give permission. In those situations, judges have to weigh what is in the ''best interest of the child'' along with the parents' wishes and the state's obligation to protect its residents.
The court decides what is in the child's best interest based on five criteria: the minor's wishes, the minor's religious beliefs, the probability of adverse side effects from treatment, prognosis without treatment, and the competency of the minor to make that decision.
But until yesterday's decision, it was unclear whether courts needed to hear directly from a ''mature minor'' about their wishes and also whether the courts needed to give those ideas weight.
''Although the judge did consider'' Demos's ''wishes and her religious convictions in this matter, he made no determination as to her maturity to make an informed choice,'' Porada wrote. Carhart ''should not have relied solely on the representations made by her attorney and her parents, but should have heard her own testimony.''
Porada added, ''it is appropriate for a judge to consider the maturity of the child to make an informed choice.''
The Appeals Court said state law is vague about how to define a ''mature minor'' who is legally capable of making important decisions.
''Our laws provide no bright line as to when a minor reaches an age to make certain decisions in life,'' Porada wrote in a footnote.
In Massachusetts, for instance 14-year-olds can be sentenced to life in prison without parole and 16-year-olds can drop out of school, consent to have sex, hold a job, and drive. Eighteen-year-olds can marry, vote, and get an abortion.
Simons said he spoke briefly with Demos yesterday and said she was delighted by the court's ruling. He said she is recovering, but still faces a possibility of needing a transfusion if her progress suddenly slows.