In the first case to question an adult's constitutional right to choose, in effect, life or death, the appeal judges placed new duties of care on doctors.
Lord Donaldson, the Master of the Rolls, ruled that while patients maintain an absolute right to refuse life-saving treatment, doctors must ensure the refusal is genuine, taken after full consultation about the consequences, and not made under the undue influence of others. If in doubt, doctors must ask the courts to intervene.
But the new guidelines - which included the drawing up of new consent/refusal documents - were immediately criticised by the Official Solicitor, David Venables, who is to challenge them in the House of Lords, and by doctors' professional bodies, who fear patients' rights have been undermined and that doctors have been faced with an impossible task.
Mr Venables said: 'I am concerned that the ruling might leave sick patients - for example those with cancer who may decide they have had enough and choose to end painful, unpleasant treatments - with the belief that their wishes could be overridden.'
He said that 'placing a forensic duty on a medical team created great problems for doctors'.
Dr Natalie-Jane Macdonald, head of ethics at the British Medical Association, said: 'The judgment has worrying implications for doctors and their relationships with patients. Reaching decisions in these cases is always hard and can be very sensitive. Doctors are suddenly being asked to take on an investigative rather than a caring role. How far are they supposed to go in discovering who may have had an influence on a patient and whether that amounted to undue influence?'
The guidelines were set out by Lord Donaldson, when he was giving detailed reasons for last week's decision that a 20-year-old woman - identified only as 'T' - should be given blood transfusions, despite her apparent written refusal. Since that decision, the condition of the woman - suffering complications following the still-birth of her baby - has improved slightly but she remains critically ill.
It was alleged that while the woman was not a Jehovah's Witness, her mother was a devout follower of the faith and wrongly persuaded her daughter to refuse blood transfusions. Witnesses oppose medical use of blood.
It was T's non-Witness father who won the court ruling overriding his daughter's refusal because of the undue influence of the mother and because T may have been lulled into a false sense of security about the availability of alternative treatments.
The Official Solicitor, who was called in to represent T's interests when she became unconscious, had unsuccessfully argued that her wishes should be paramount.
Yesterday, Lord Donaldson, sitting with Lords Justice Butler- Sloss and Staughton, said: 'Society's interest is in upholding the concept that all human life is sacred and that it should be preserved if at all possible.'
Law report, page 22