Legal permission will no longer be required to end care for patients in a permanent vegetative state, a judge has ruled.
Until now a judge must also consent, even if medics and relatives agree to withdraw nutrition from a patient.
But in what been described as a landmark decision, those cases will no longer have to come to court.
The Official Solicitor, appointed by the state to act for such patients, is likely to appeal against the ruling.
Doctors are able to withdraw treatment from a patient - if relatives consent - under various circumstances without needing court approval.
Mr Justice Jackson, who sits in the Court of Protection, made his ruling in a case concerning a 50-year-old woman who suffered from a degenerative illness for 14 years.
The patient, known in court as M, had Huntington's disease and was bed-ridden in hospital and fed by a tube.
She had shown no sign of awareness for 18 months, the court heard, and Mr Justice Jackson agreed with her family and doctors that withdrawing nutrition from her would be in her best interests.
The tube was removed and she died in August.
Mr Justice Jackson said in his view the case should not have come to court.
"The decision about what was in M's best interests is one that could lawfully have been taken by her treating doctors, having fully consulted her family and having acted in accordance with the MCA (Mental Capacity Act) and with recognised medical standards," the judgement said.
Analysis: Clive Coleman, BBC legal affairs correspondent
So long as relatives agree, and it's in the best interests of a patient in a minimally conscious or vegetative state, doctors can withdraw all sorts of treatment that will result in the end of someone's life.
These include, for instance, the withdrawal of life-saving dialysis. Doctors do not need the permission of a court to be able to do this.
However, withdrawing food and water - the most basic requirements for life - has been handled differently, and for many years has needed the approval of a court.
It's been treated as an exception, in part, perhaps, because of the emotional and psychological significance of the decision to remove sustenance from a person.
This has resulted, some experts believe, in individuals spending longer on life support in a vegetative state than was necessary because hospitals have shied away from going to court due to the expense and bureaucracy involved.
Today's ruling makes clear that as things stand, courts need not be involved in these sorts of cases, so long as doctors and families are in agreement, and the removal of food and water are in the best interests of the patient.
Mr Justice Jackson said that even in M's case - when family and doctors agreed - legal costs reached £30,000.
Law firm Irwin Mitchell, which represented M, described Mr Justice Jackson's ruling as a "landmark" decision for a "previously unclear" law.
A spokesman said: "The family argued that major life and death decisions happen every day in hospital and do not always need to come before the court. NHS doctors supported this argument."
For nearly 25 years, these decisions have been referred to the Court of Protection, even where doctors and families agree.
This followed a House of Lords ruling that Tony Bland, who was left in a persistent vegetative state after suffering severe brain damage in the 1989 Hillsborough disaster, should be allowed to die.
Wednesday's ruling removes this exception and paves the way for a change in the way such cases are handled by hospitals.
Sarah Wootton, chief executive of the campaign group Compassion in Dying, said the ruling was "a helpful step towards a clearer, more person-centred view of end-of-life care".
"When all parties - family, the hospital and treating doctors - are agreed on what someone would have wanted for their care, it seems absurd to require a costly court process to confirm this."
Research by the BBC established last year that there were more than 100 patients in England and Wales in permanent vegetative or minimally conscious states.
One patient had been in this condition for more than 20 years.