The UK Supreme Court has rejected an appeal by the parents of sick baby Charlie Gard, over plans to take him to the US for treatment.
Chris Gard and Connie Yates want the 10-month old, who suffers from a rare genetic condition, to undergo a therapy trial.
His mother broke down and screamed as the decision was announced.
Charlie can stay on life support for 24 hours to give the European Court of Human Rights a chance to give a ruling.
He has been in intensive care at Great Ormond Street Hospital since October last year.
The hospital said therapy proposed by a doctor in America is experimental and that Charlie’s life support treatment should stop.
Charlie has mitochondrial depletion syndrome, a rare disorder that affects the genetic building blocks that give energy to cells.
The family division of the High Court agreed two months ago that the hospital could withdraw Charlie’s life support.
His parents have raised more than £1.3m through an internet appeal, in the hope they could take him to America for an experimental treatment.
Specialists in the US had offered a therapy called nucleoside.
Katie Gollop QC, leading Great Ormond Street’s legal team, said the case was “sad” but not “exceptional”.
She said the couple seemed to be suggesting that “parents always know best”.
“Fundamentally the parents don’t accept the facts,” she said. “They don’t accept that nucleoside therapy will be futile.”
The court had earlier heard how Charlie could not could see, hear, move, cry or swallow.
Ms Gollop added: “He is on a machine which causes his lungs to move up and down because his lungs cannot go up and down.
“Charlie’s condition affords him no benefit.”
Following the ruling Ms Yates screamed outside court: “How can they do this to us?”
“They are lying. Why don’t they tell the truth?”, she said.
Charlie’s life support machine will continue until Friday at 17:00 BST to give the parents a chance to hear if they can take their case to the European Court of Human Rights, the court said.