The American Medical Association yesterday refused to provide a grand jury in Chicago with the name of a young doctor whose unsigned admission of a mercy killing was published last month in the AMA's weekly journal.

In the column titled "It's Over Debbie," the physician described how he deliberately gave a tormented 20 year-old cancer patient an overdose of morphine.

The column's publication renewed a longstanding debate over mercy killing and provoked sharp reactions from doctors and lawyers around the nation. Yesterday, a grand jury in Chicago, where the Journal of the American Medical Association is published, delivered a subpoena to the AMA demanding all records concerning the column, including the original article, the author's cover letter and any memos discussing the story.

"This is a clear First Amendment issue," said Kirk Johnson, the AMA general counsel. "I assume the article would not have been published if not for the confidence conferred on the writer. It {the subpoena} is a direct intrusion on that confidence and it is unacceptable."

The doctor's action was against the law and violated accepted medical guidelines, according to the AMA and other medical experts. But the issue is one that has caused increasing debate as technological advances have helped keep the critically ill alive longer.

The AMA strongly opposes euthanasia, and officials said they wanted to stress that publishing the story should not be interpreted as an endorsement of the action. Late last week, however, the organization's board of trustees said it supported the editors' decision.

The board said euthanasia is an issue of urgent importance and the trustees did not want to be in the position of preventing the free flow of information.

Cook County State's Attorney Richard Daley became interested in the case because the journal is published in Chicago, but there is no indication where the incident took place. A spokesman for Daley declined comment yesterday because the incident is under investigation.

In the column, a gynecology resident described a visit to the bedside of a cancer patient. He found a young woman in agony who weighed no more than 80 pounds. Her chart said she had not eaten or slept in two days.

"Let's get this over with," the doctor quoted the woman as saying.

The journal received hundreds of letters, according to the AMA, most of them objecting to the article. But many doctors say in private -- and have for some time -- that mercy killing has gained a new acceptability in their profession and among Americans.

Both the California and New York legislatures have considered and then rejected legalizing euthanasia. The majority of legislators in both states decided that, no matter what the circumstances, taking the life of a patient cannot be justified.

"The issue here is not what is legal in medicine," Johnson said. "Dr. George Lundberg, the editor of JAMA, has invoked the reporter's privilege, which protects confidential sources from disclosure."

The Illinois Reporters Privilege Act says that someone seeking confidential information must prove in a hearing that there is no other available source for the information and that the disclosure is clearly in the public interest.

"Because the state's attorney office has not complied with the requirements of the act, JAMA will not comply with the subpoena," Johnson said. He left open the possibility, however, that the journal's editors would comply with a formal court order if the prosecutor's office went through the proper steps.