Doctors have been put in "an impossibly difficult position" by a judge's ruling that a terminally ill man should not be denied life-prolonging treatment, the Court of Appeal was told yesterday. The "right to live" judgment raises the risk that physicians will be forced to inflict procedures on dying patients that do them more harm than good, it was claimed.

The General Medical Council is appealing against a decision by Mr Justice Munby last year that Leslie Burke, who suffers from the degenerative brain condition cerebella ataxia, should not be denied artificial nutrition and hydration during the final stages of his illness.

Mr Burke, 45, who is confined to a wheelchair, brought the case because he was concerned that doctors would withdraw feeding and hydration when he was too incapacitated to object, leaving him to starve to death.

Guidelines drawn up by the GMC stated that if a patient's condition has deteriorated so severely and the prognosis is so poor, doctors can stop artificial feeding if they believe it would be "too burdensome in relation to the possible benefits".

In his judgment, Mr Justice Munby partly upheld Mr Burke's claim and told the GMC to redraft its advice to doctors. The GMC is now appealing against that ruling, saying it threatens the doctor-patient relationship and is insufficiently clear about what changes are required.

Philip Havers QC, representing the GMC, told three appeal judges, headed by the Master of the Rolls, Lord Phillips of Worth Matravers, that the law did not state that a patient has a right to require the provision of any particular form of treatment. He said the conclusion of the earlier judgment was not in the best interests of patients because, firstly, doctors would have to provide treatment which they knew would be of no benefit or could be harmful.

Second, to require a doctor to do so was destructive of the relationship between doctor and patient.

Third, said Mr Havers, such a conclusion "puts the doctor in an impossibly difficult position, for a doctor should never be required to provide a particular form of treatment to a patient which he does not consider to be clinically appropriate. "Doctors are under a professional duty not to provide such treatments to patients." Mr Havers said the main purpose of the GMC was to "protect, promote and maintain" the health of the public, including those who need life-prolonging treatment.

The case is being closely watched by doctors, and by pro- and anti-euthanasia campaigners, as it goes to the heart of the debate over end-of-life decisions. Lawyers representing Mr Burke say Mr Justice Munby's judgment represents a shift in the balance of power away from the doctor to the patient, and from the medical profession to the courts. But the medical profession is concerned that the ruling amounts to allowing "treatment on demand".

Mr Burke, a former postman from Lancaster, was in court for the start of the hearing, which is expected to last at least a week.

In a separate case, the High Court and the Court of Appeal have upheld a decision by doctors not to resuscitate the disabled 18-month old baby Charlotte Wyatt if she stops breathing. They believe it would not be in her best interests.