A new phase in the continuing controversy over abortion opened yesterday when the Supreme Court agreed to rule on a 1974 Massachusetts law that requires women under 18 who aren't married, divorced or widowed to get written parental or judicial consent for abortions.

A panel of three federal judges struck down the law last May, holding that "a minor has a basic constitutional right to an abortion" that the state can limit only to protect her "from the special consequences of her minority - immaturity and the lack of informed understanding."

The panel held that the law denies due process to "mature" minors, burdens those whose best interests require parents to be ignorant of their pregnancies, and is written in broad language that impermissibly chills decisions to abort.

A minor may have several reasons to keep her parents in ignorance of her pregnancy, Circuit Judge Bailey Aldrich wrote for the panel. He cited parents who may be "injured by the shock," be "child- abusers," or who may be potentially "hostile." Other parents may insist on an unwanted marriage or on continuance of the pregnancy, or prevent their daughter from going to court, he added.

Nothing that the law provides no penalties for improper withholding of parental consent, the judge said that a teen-ager in such a circusmstance could be harmed by seeking court approval and therefore might resort instead to an illegal and dangerous abortion. If she went to court anyway, he said, she could ruin whar remained of her family ties.

Consequently, Aldrich said, the law puts the minor "in a no-win situation. If she loses the judicial proceedings, it will be a personal blow . . . if she wins . . . she is likely to find herself in an even worse situation."

In the state's successful petition for review, Attorney General. Francis X. Belloti wrote that the law "in large measure simply codifies the traditional Massachusetts common-law rule that a physician may not perform surgery upon a minor without first securing parental consent," and that "simply structures the abortion decision-making process to protect the best interests of adolescents and children."

By contrast, Aldrich wrote that except for "far more serious" sterilization, "abortion is the only form of surgery to which a mature minor may not consent, although the evidence shows that many other forms are far more complicated and dangerous."

He also accuses the state of neglecting to point out that a properly performed first-trimester abortion is an alternative sometimes involving lesser risks than continued pregnancy and childbirth.

The panel had struck down the law once before, in April 1975. But the Supreme Court nullified and sent back the decision in july 1976, at the same time that it invalidated a Missouri "blanket rule" of parental consent for minors seeking abortions.

The court took other actions. MIRANDA RULES

In the so-called Miranda case in 1966, the court adopted a rule that police interrogation of a suspect who says he or she wants a lawyer must cease until the lawyer arrives.

Complying literally with the rule, a Los Angeles police officer investigation the murder of film publiscist Robert Yeager in 1976 told suspect "Michael C," 16, that "you don't have to talk" without an attorney. But the juvenile wanted at his side his probation officer, who later testified that he had instructed Michael "to contact me immediately" at any time when "he has a police contact."

The police officer refused to summon the probation officer. Michael then confessed and was convicted. But the California Supreme Court reversed, holding that the confession had to be excluded because a juvenile's call for help from his probation officer is constitutionally equivalent to a call for an attorney. Yesterday, the U.S. high court agreed to review the ruling. ADDITIONALLY

The court agreed to review rulings that:

Struck down requirements that persons complaining of age discrimination in employment go to a state agency before going to federal court.

Invalidated a Texas law intended to let the state take custody of children whose parents batter them.

Upheld convictions by nonunanimous six-member juries.

The court declined to grant reputed Cosa Nostra leader Russell Bufalino's plea for review of his extortion conviction.