AN FRANCISCO, Aug. 9 — In September 1993, Robert Wendland of nearby Stockton crashed his pickup truck, an accident that left him brain-damaged and unable to walk, talk, eat or drink, or in any way communicate his wishes. Two years later his wife, Rose, asked doctors to remove the feeding tubes that kept him alive, saying he had told her not long before the crash that he would never want to live in so helpless a condition.

But Mr. Wendland's mother and sister objected, noting among other things that he was conscious, if minimally so, and not comatose. They carried their case all the way to the California Supreme Court.

Today the justices ruled in their favor, finding that families have no right to stop life support for conscious patients who are not terminally ill, and who have not left explicit instructions allowing them to do so or formally appointed anyone to make health care decisions in the event of incapacity.

Although Mr. Wendland, still attached to feeding tubes, died of pneumonia last month at the age of 49, the court had retained the closely watched case to clarify law regarding the right of families to disconnect life support systems.

In its 6-to-0 decision today, the court said that "absent clear and convincing evidence" that Rose Wendland's decision was in accordance with her husband's own wishes or best interest, it would not have allowed the removal of life support.

The Associated Press Robert Wendland, the focus of the ruling on Thursday, was photographed in his hospital bed in May. He died in July, still attached to feeding tubes.

Courts have previously allowed the removal of life support in cases where a patient is terminally ill or in a permanent comalike state, most famously a quarter-century ago in the precedent-setting case of Karen Ann Quinlan in New Jersey. But the law has been unclear as to how families can proceed when patients are conscious but unable to express their wishes.

The justices emphasized the narrow scope of their ruling, saying it affected only cases involving patients who are conscious, who would die without life support, and who have not left formal directions for health care or legally appointed anyone to make such decisions should they ever be unable to make them.

"Our conclusion," Justice Kathryn Mickle Werdegar wrote for the court, "does not affect permanently unconscious patients, including those who are comatose or in a persistent vegetative state."

Jon Eisenberg, an Oakland lawyer representing more than 40 medical ethicists who had urged the court to uphold Rose Wendland's wishes, said the ruling meant that "if you want to have a say in your end-of-life decision making, you'd better put it in an advance, written directive." He added, "The problem here is, I don't know how you do that in a manner that covers all of the possibilities."