A woman has persuaded a judge that her 50-year-old mother - who wants to die because she thinks that she has lost her "sparkle" - is mentally capable of deciding to refuse medical treatment in hospital.
The woman told Mr Justice MacDonald that no-one in the family wanted her mother to die.
She said she thought that her mother had made a "horrible" decision.
But she argued that her mother, who has a grandchild, understood what she was doing and was mentally capable of making decisions about treatment.
The judge ruled in the woman's favour late on Friday after analysing the case at an eight-hour hearing in the Court of Protection, where issues relating to sick and vulnerable people are considered, in London.
A lawyer who represented the woman at the hearing today said the "result" was right - but she said there were no winners.
Solicitor Laura Hobey-Hamsher said the judge had recognised the 50-year-old woman for "who she was".
The woman's mother had damaged her kidneys when taking a drug overdose in a failed suicide bid and was now refusing dialysis, Mr Justice MacDonald was told.
Specialists argued she had a "dysfunction of the mind" which made her unable to make decisions about treatment.
They asked the judge to rule that it would be in her best interests if treatment was "imposed" and restraint and sedation used if necessary.
But Mr Justice MacDonald dismissed the application.
The judge said he was not satisfied that hospital bosses had proved that she lacked the mental capacity to decide to refuse dialysis - although he said they had been right to bring the case to court.
He said he would publish his detailed reasons for his decision in the near future.
Another judge, who oversaw the case at an earlier stage, had ruled that none of the people involved could not be identified.
But the London-based King's College Hospitals NHS Foundation Trust, which asked for a ruling, can be named.
The 50-year-old woman had a number of daughters - including one in her teens - and a grandchild, the judge heard.
She had faced a number of "problems" before attempting suicide - including failed marriages and financial difficulties, he was told.
The judge analysed evidence from psychiatrists and medics.
One daughter told him that her mother's life had "to all appearances" been fairly glamorous.
And she said her mother did not want to be poor, "ugly" and "old".
"She has said the most important thing for her is her sparkly lifestyle," said the daughter.
"She kept saying she doesn't want to live without her sparkle and she thinks she has lost her sparkle."
The daughter said family members would devastated if her mother died.
But she added: "We think it is a horrible decision. We don't like the decision at all. But I cannot get away from the fact that she understands it."
Neither the daughter nor other family members today wanted to discuss the case.
But Ms Hobey-Hamsher, who works for law firm Bindmans, said: "No child should ever have to persuade either doctors or a court that when her mother says she wants to die, she knows her own mind.
"What was right was that the court recognised her mother for who she was: a unique individual, able to make her own decision, in her own way, in her own time, and for the reasons important to her."