When Charlie Gard died, his parents said their son would make a difference to people's lives for years to come.
Chris Gard and Connie Yates have spent the months since his death developing 'Charlie's Law'.
They have worked with doctors, ethicists and politicians to try to find a way to avoid other families being taken to court.
This comes as leading paediatricians say they are concerned about the effect of such high-profile cases on medics.
Charlie Gard's parents first got worried about his health when he was about six weeks old. He didn't seem to be as strong as other new-borns. Two weeks later, they took him to hospital.
He didn't ever come home again. But their flat seems as if a baby lives there. The changing table is in the middle of the room, still stocked with tiny nappies and clothes.
Photos of their son dominate the room, hanging on the wall, slotted into frames and lying on the sideboard. There are cards propped up there too.
Some were sent by family congratulating Chris and Connie when they found out Connie was pregnant. Others offer sympathy after Charlie's death.
Connie says they aren't ready to get rid of his things yet because it "feels like he's always with us". Charlie had mitochondrial depletion syndrome, a condition which causes progressive muscle weakness and brain damage. He passed away a few weeks before his first birthday.
It came after a long, bitter and very public legal battle between his parents and doctors. The medical team at Great Ormond Street had said there was no cure or treatment. But his parents wanted to try experimental therapy in the United States.
His parents say going to court was "completely and utterly daunting, terrifying". So they want Charlie's Law to help prevent other cases from getting to that stage.
Connie says: "It was so, so, so hard for us to go through what we went through, and we don't want it to happen to anyone else again." They are looking for an MP to sponsor a Private Member's Bill in Parliament.
One key part of the law would be having independent medical mediators involved in disagreements as early as possible. Great Ormond Street says "mediation is one of the important ways in which we work with families to reach agreements, in the best interests of the child."
However, Charlie's parents claim that they asked for mediation months before his death, but the hospital refused. Chris explains: "If mediation had taken place with an independent mediator, we would have felt our voices were being listened to." Great Ormond Street says it did offer mediation in the final few days of his life.
Sarah Barclay is director of the Medical Mediation Foundation. She says she mediates between 5 and 10 conflicts a year: "Sometimes it feels like there's a bit of a battle developing." She explains: "Mediation is always surprising in the way it can break through really intractable conflicts.
"Just because of what mediators do, they're there to support everybody.
"They're there to listen to all sides of a story and to say, they all matter."
Charlie's parents say they understand that these situations cannot simply be about doing whatever families want. For them, a key part of "Charlie's Law" would be a change to how judges reach their decision.
Currently, judges must assess only what is in the best interest of the child. But Chris Gard and Connie Yates want judges to ask instead if the parent's choice of treatment would cause significant harm to the child. If not, they think families should be allowed to try their option.
Charlie's case was not the first disagreement between doctors and families to become headline news. But it was the first time social media played such a big role in the conflict, as supporters called themselves "Charlie's Army."
And in April, another case with another family and another hospital. Alfie Evans' parents were also taken to court, but their son died when he was 23 months old.
At one stage, police had to block protestors from storming Alder Hey hospital in Liverpool. The Royal College of Paediatrics and Child Health is worried about these developments.
It says: "The intense criticism of health professionals involved in recent cases has been traumatic and distressing. "At a time when there are already substantial problems with staffing levels in NHS hospitals, there is real concern that this will make it harder to recruit and retain vital staff.
"This will ultimately impact on services available for all patients and their families."
Dr Hilary Cass is Chair of Trustees for the charity Together for Short Lives. She echoes this concern: "High profile cases have polarised thinking and polarised views.
"People who previously would have made carefully considered decisions together are now doing so in the crucible of a very large public debate.
"That increases the stress on everyone involved."
Doctors and charities stress that these cases are the exception to the rule. There are at least 49,000 children and young people in the UK with illnesses that may cut their lives short.
Medical advances mean more sick babies are living for longer, so that number will increase. Charlie Gard's parents feel that unless the law changes, there will be more cases like theirs in the courts.