Two parents whose baby son is seriously ill are fighting a court battle against doctors to keep him alive.
Specialists at Great Ormond Street Hospital want to withdraw life-support for seven-month-old Charlie Gard, who suffers from a rare genetic condition meaning he is deaf and unable to cry.
Medics believe that further treatment would unnecessarily prolonging Charlie's suffering.
But his parents, Chris Gard, 32, and Connie Yates, 31, want to keep him on life-support so they can fundraise and take Charlie to the US for pioneering treatment.
A decision whether or not to withdraw life-support is now down to a High Court judge.
The judge at London's High Court heard that Charlie, who was born in August last year, has a form of mitochondrial disease - a condition which causes progressive muscle weakness.
His parents, the court was told, are "utterly devoted" to him, with the judge describing the case as "one of the saddest" it had come across.
Katie Gollop QC, for the hospital, said that doctors felt "every day that passes is a day that is not in the child's best interests."
Sophia Roper, representing Charlie's parents, said: "His parents believe that he is in much better shape than the hospital does."
The court heard that Charlie would have to fly in an air ambulance with nurses if he went to America.
Lawyers said a hospital in Spain had decided against accepting him as a patient.
A full hearing on the matter is due in early April.