The parents of a seven-month-old baby who are challenging doctors in court to keep him on life support say they deserve the right to judge his care.
Connie Yates's and Chris Gard's son, Charlie, is receiving 24-hour treatment at London's Great Ormond Street hospital for a rare genetic condition.
With no accepted cure for his condition, the hospital believes Charlie should be allowed to die.
But his parents say pioneering US treatment could save his life.
They told the BBC's Victoria Derbyshire programme that they will continue to fight for their child's survival.
"He can move his mouth, he can move his hands. He can't open them fully, but he can still open his eyes and see us, in response to us.
"We don't feel he's in pain at all."
The couple, who live in London, want to take Charlie to the US, where they believe he may have a chance of surviving if he receives pioneering treatment.
"We just want to have our chance. It would never be a cure but it could help him live. If it saves him, amazing," Miss Yates said.
"I want to save others. Even if Charlie doesn't make it through this, I don't ever want another mum and their child to go through this."
Charlie, who was born on 4 August, was admitted to Great Ormond Street in October after developing aspiration pneumonia.
He was later diagnosed with mitochondrial depletion syndrome - a condition that causes progressive muscle weakness.
"He's only one of 16 in the whole world affected by it. Chris and I are both carriers," Miss Yates said.
"It's so unbelievably rare we would have the same fault on the same gene. Very, very rare."
Miss Yates has launched a campaign - #CharliesFight - which has raised more than £220,000 of the £1.2m she believes is needed for Charlie to receive the treatment abroad.
"I want the judge to have the belief I have in this medication. [Great Ormond Street Hospital] have never used this medication," Miss Yates said.
"The judge needs to trust us, we are his parents. We don't want him to suffer. If he is suffering then of course I would let him go."
She added: "Someone else in the world is willing to take him and help him. Why can't we try that?"
A spokesperson for Great Ormond Street Hospital for Children NHS Foundation Trust said: "Charlie has a very rare and complex disease, for which there is no accepted cure.
"Charlie was very unwell when he was admitted to Great Ormond Street Hospital and has remained under 24-hour care on our intensive care unit.
"But his condition has continued to deteriorate and we now feel we have exhausted all available proven treatment options.
"We cannot imagine how hugely distressing this is for his family.
"We continue to support them in every way we can, while advocating, what we believe, is best for Charlie."
Watch the Victoria Derbyshire programme on weekdays between 09:00 and 11:00 on BBC Two and the BBC News Channel.