A High Court judge has ruled that doctors can stop providing life-support treatment to 21-month-old Alfie Evans against his parents' wishes.
Doctors at Alder Hey Children's Hospital in Liverpool said continuing to provide life support treatment was "unkind, unfair and inhumane".
Alfie's parents Kate James and Tom Evans, who are both in their 20s, wanted treatment to continue as they believe that he is responding to it.
Speaking outside the High Court in London Mr Evans said he would fight the decision: "My boy is strong and he's comfortable, this isn't over this is just the start.
"I'm not giving up. My son isn't giving up.
"No one and I repeat no one in this country is taking my boy away from me, no one.
"My son is two years of age and he's being sentenced to the death penalty.
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"We got the false impression that we were going to at least get the dignity to go home with him but instead now they want him dead on Friday.
"He's doing brilliant, he's doing the best he can and they want him dead on Friday. Why do they want my son dead so quick," said Mr Evans.
Mr Justice Hayden said he accepted medical evidence which showed further treatment was futile, adding that he had reached his conclusion with great sadness.
"Alfie's need now is for good quality palliative care.
"He requires peace, quiet and privacy in order that he may conclude his life ad he has lived it, with dignity," he said.
He paid tribute to Alfie's parents and to doctors and nurses at Alder Hey.
Alfie's mother left the court hearing before Mr Justice Hayden reached his conclusion and his father broke down as the decision was announced.
The judge had previously heard that Alfie, who was born on May 9 2016, was in a "semi-vegetative state" and had a degenerative neurological condition doctors had not definitively diagnosed.
The judge had visited Alfie in hospital and has praised his parents and said they had tried to explore every avenue and leave no stone unturned.
Outside the children's hospital around 30 members of "Alfie's Army" were supporting the family's campaign as they awaited the decision.
As news of the decision filtered through, supporters stood in silence, wiping away tears and exchanging hugs.
In a statement, Alder Hey Children's Hospital said: "Our aim is always to try and reach an agreement with parents about the most appropriate care plan for their child. Unfortunately there are sometimes rare situations such as this where agreement cannot be reached and the treating team believe that continued active treatment is not in a child’s best interests.
"The Trust referred this case to the Family Division of the High Court to seek a determination as to what treatment Alfie should receive in his best interests. The Children and Family Court Advisory Support Service (CAFCASS) also considered the case and provided Alfie with independent representation.
"The Court has today made a decision about Alfie’s future care and treatment. We understand that this is a very difficult time for Alfie’s family and we will continue to work with them to agree the most appropriate palliative care plan for Alfie."