A judge is to be asked to decide whether doctors should stop providing life support to a woman in her 20s who suffered a serious brain injury when attempting suicide.
Specialists say the woman has been left in a "permanent vegetative state" and her "prospect of recovery" is "significantly less than 1%".
They want a judge in the Court of Protection - where issues relating to sick and vulnerable people are analysed - to give them permission to stop providing artificial nutrition and hydration.
The woman's parents are against such a move.
A judge is expected to make a ruling, after analysing evidence at a Court of Protection hearing, later this year.
Preliminary issues were discussed at a Court of Protection hearing in London on Friday.
Mrs Justice Roberts was told the woman had attempted to hang herself two years ago and had been found by her father.
Doctors said she had not regained any "level of conscious awareness".
The judge ruled the woman could not be identified.
She heard the Court of Protection application had been made by the Buckinghamshire Healthcare NHS Trust - which had responsibility for the woman's care.
The woman's father was at the preliminary hearing. Her mother - who is unwell - watched via a video link.