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A Christian rights organisation has labelled as "ludicrous" a High Court judgement ruling that life-support treatment for 12-year-old Archie Battersbee should end.
The campaign group that has been supporting Archie's family had said the ruling set a "troubling and dark precedent".
On Monday, a High Court judge ruled that life-support treatment for Archie should end, though his family have already vowed to appeal and his mother said the hospital would now be facing "the biggest fight ever".
Archie has been on a ventilator and receiving life-support treatment since early April when he suffered brain damage at home in Southend.
After the ruling was announced, Andrea Williams, chief executive of the Christian Legal Centre, said: "This ruling is a devastating moment for Archie and his family.
"The idea that death can be declared on the balance of probability is frankly ludicrous.
"Life is the most precious gift that we have. This ruling sets a troubling and dark precedent."
Monday's ruling from the judge said that Archie had died on 31 May, shortly after MRI scans taken that day.
The judge added: “I find that irreversible cessation of brain stem function has been conclusively established. I give permission to the medical professionals at the Royal London Hospital to cease to ventilate mechanically Archie Battersbee.”
Ms Williams from the Christian group said the ruling would not deter the family and they intended to fight on.
"This case has raised significant moral, legal and medical questions as to when a person is dead.
"Archie’s parents do not accept that he is dead and are fighting courageously for his life.
"They will not give up now and intend to appeal. We will continue to stand with the family and continue to pray for a miracle."
Doctors treating Archie at the Royal London Hospital in Whitechapel, east London, argued that the boy was "brain-stem dead" and because of that, life-support treatment should end.
Archie's parents, Hollie Dance and Paul Battersbee, said the youngster's heart was still beating and so treatment should continue.
The judge heard that Archie suffered brain damage in an incident at home in early April.
Ms Dance told how she found him unconscious with a ligature over his head on 7 April and believes he may have been taking part in an online challenge.
The youngster has not regained consciousness.
Lawyers representing Archie's family told the judge that his heart is still beating - and his mother said he had gripped her hand.
They also argued there was an issue as to whether "the correct procedure" had been followed, and whether the "family's views" had been taken into account.