"Urgent review and reform" is needed in light of Archie Battersbee's death, a group that has been supporting his family has said.
The Christian Legal Centre has offered its condolences to the 12-year-old's loved ones at this "tragic moment".
Chief executive Andrea Williams said: "The events of the last few weeks raise many significant issues including questions of how death is defined, how those decisions are made and the place of the family.
"No one wants to see other families experience what they have been through."
Archie had been at the centre of a lengthy legal dispute after he was seriously injured in an incident at his home in Southend, Essex, in April.
He had been in a coma since then and had not regained consciousness, being kept alive by a combination of medical interventions, including ventilation and drug treatments.
Earlier this year, his parents said that the youngster's heart was still beating and that he had gripped his mother's hand.
But doctors treating the boy had declared Archie to be "brain stem dead", and argued that the youngster should be disconnected from a ventilator.
This prompted a lengthy but unsuccessful fight in the courts to continue his life support treatment in the hope he would recover.
Archie's family had later made bids to the High Court, Court of Appeal and European Court of Human Rights to have him transferred to a hospice to die, but all legal routes were exhausted.
'We hope no family goes through this'
He was taken off medication at 10am on Saturday morning, and his mother Hollie Dance said he died at 12.15pm that afternoon.
Speaking on behalf of the family, Ella Rose Carter - the fiancée of Archie's eldest brother Tom - said: "There is absolutely nothing dignified about watching a family member or a child suffocate.
"We hope no family has to go through what we have been through. It's barbaric."
The Christian Legal Centre has vowed to continue supporting Archie's family, and said it was thankful for the widespread public support they had received.
Alistair Chesser, chief medical officer at Barts Health NHS Trust - which oversaw Archie's care - said in a statement: "Members of his family were present at [Archie's] bedside and our thoughts and heartfelt condolences remain with them at this difficult time.
"The trust would like to thank the medical, nursing, and support staff in the paediatric intensive care department who looked after Archie following his awful accident.
"They provided high-quality care with extraordinary compassion over several months in often trying and distressing circumstances. This tragic case not only affected the family and his carers but touched the hearts of many across the country."
The 'golden thread' running through the case
The family's love for Archie was described by one judge as the "golden thread" running through the case.
Speaking to Sky News earlier this week, Ms Dance, said: "I don't think there's been a day that hasn't been awful, really. It's been really hard.
"Despite the hard, strong face and appearance, obviously, in front of the cameras, up until now, I've been pretty broken."
She added: "I've done everything that I promised my little boy I'd do, and I've done it."