Three courts in Britain agreed with the hospital, as did the European Court of Human Rights, which last week rejected a last-ditch appeal by Charlieâs parents.
But Pope Francis and Mr. Trump have also weighed in, adding another dimension to an extraordinarily thorny bioethical and legal dispute that pits Britainâs medical and judicial establishment against the wishes of the childâs parents.
Judges in the case have acknowledged that the case highlights differences in law and medicine â and an American willingness to try anything, however unlikely the possibility of success â but have held that prolonging the infantâs life would be inhumane and unreasonable. The case echoes the one of Terri Schiavo, a Florida woman who was left in a persistent vegetative state after a cardiac arrest and was also the subject of a court battle.
A Vatican spokesman, Greg Burke, told Vatican Radio on Sunday that the pope had been following the parentsâ case âwith affection and sadness,â praying âthat their desire to accompany and care for their own child to the end is not ignored.â
Mr. Trump, who was not known to have previously expressed a view on the matter, wrote on Twitter on Monday that if the United States could help, âwe would be delighted to do so.â
Both the pope and the president stopped short of criticizing the court rulings or the hospital. Helen Aguirre FerrÃ©, the director of the White House office of media affairs, said Mr. Trump had decided to speak out after he learned about âthis heartbreaking situation.â Mr. Trump has not spoken with the family, she said, and does not want âto pressure them in any way.â
âThe president is just trying to be helpful if at all possible,â she added.
Charlie was born on Aug. 4, 2016, with encephalomyopathic mitochondrial DNA depletion syndrome. He is thought to be one of only 16 children globally with the condition, the result of a genetic mutation.
Brendan Lee, the chairman of the department of molecular and human genetics at Baylor College of Medicine, who is not involved the case, said in a phone interview that mitochondrial depletion syndrome has no cure. âTreatments involve different types of vitamin supplementation, but none have been shown to definitively work through studies,â he said.
Charlieâs parents, Connie Yates and Chris Gard, both in their 30s, have been waging a long and wrenching legal battle to keep him alive. They have raised more than 1.3 million pounds, or about $1.7 million, to help finance experimental treatment in the United States. There is also an international campaign, with an online petition and there have been street protests in front of Buckingham Palace.
Charlie has been treated since October at Great Ormond Street Hospital, where doctors eventually decided that withdrawing life support was the only justifiable option. âAlthough Charlieâs parents have parental responsibility, overriding control is by law vested in the court exercising its independent and objective judgment in the childâs best interests,â the hospital said in a statement laying out its position.
The High Court ruled that Charlie would face significant harm if his suffering were to be prolonged without any realistic prospect of improvement. Moreover, it said the experimental treatment, known as nucleoside therapy, would not be effective.
Money is not at issue; an academic medical center in the United States has offered to provide the experimental treatment. But a neurologist at the hospital, who has offered to oversee the treatment, told the court by telephone: âI can understand the opinion that he is so severely affected by encephalopathy that any attempt at therapy would be futile. I agree that it is very unlikely that he will improve with that therapy.â
Neither the hospital nor the neurologist was identified in court documents, and the White House has declined to identify either.
The Court of Human Rights ruled last week that the British courts had acted appropriately in concluding that âit was most likely Charlie was being exposed to continued pain, suffering and distress, and that undergoing experimental treatment with no prospects of success would offer no benefit, and continue to cause him significant harm.â
The case has drawn attention to important differences in legal systems.
Claire Fenton-Glynn, a legal scholar at the University of Cambridge who studies childrenâs rights, said that under British law, the courts were the final arbiter in medical disputes about the treatment of children.
She noted a 2001 case of conjoined twins, Jodie and Mary, who were born sharing an aorta. Separating the twins would lead to the death of the weaker twin; if they were not separated, both would die. A court ruled that the twins should be separated against the wishes of their parents; as expected, one died.
Courts in the United States are less inclined to get involved when there are disputes between parents and doctors, said Professor Moreno of the University of Pennsylvania, stressing that it was usually left to doctors, in consultation with parents, to decide on a childâs treatment.
He noted the case of Baby Jane Doe, who was born in 1983 with spina bifida and whose parents declined to approve surgery to prolong her life. That case led to a law, signed by President Ronald Reagan, that defined instances in which withholding medical treatment from infants could be considered child abuse, but also provided that in certain cases doctors and parents might choose to withhold treatment from seriously handicapped babies when such action would merely prolong dying.
G. Kevin Donovan, the director of the Pellegrino Center for Clinic Bioethics at Georgetown University Medical Center and a professor of pediatrics, said that in the United States, if parents insisted on continuing life-prolonging treatment against a doctorâs advice, the child would simply be transferred to another institution willing to comply with the parentsâ wishes.
âIt doesnât seem to be a supportable position morally or ethically,â he said of the stance taken by the hospital in London, adding that what is legal and what is ethical are not always the same.
In the Schiavo case, her husband, who was her legal guardian, wanted to have her feeding tube removed, but her parents disagreed, setting off a seven-year fight that ended in 2005, after courts ruled in the husbandâs favor. Life support was removed from Ms. Schiavo, who died at 41.
In that case, too, the pope, then John Paul II, and the president, George W. Bush, weighed in. Mr. Bush signed an act of Congress allowing federal courts to intercede in the case. But their interventions did not ultimately affect the outcome.
There was no immediate response to Mr. Trumpâs statement from Charlieâs parents, who last week appeared to accept the finality of the courtsâ rulings. Photographs of the couple sleeping with their sick child have circulated on social media recently.
âWe are really grateful for all the support from the public at this extremely difficult time,â Ms. Yates said on Friday. âWeâre making precious memories that we can treasure forever with very heavy hearts. Please respect our privacy while we prepare to say the final goodbye to our son Charlie.â
There was also no immediate reaction from the hospital.
âIn Charlieâs case we have been discussing for many months how the withdrawal of treatment may work,â the hospital said. âThere would be no rush for any action to be taken immediately.â It added that it would consult the family and that âdiscussions and planning in these situations usually take some days.â