A couple who want to take their sick baby son to the US for treatment are hoping to take their case to the European Court of Human Rights after losing a fight in the Supreme Court.
Chris Gard and Connie Yates want 10-month-old Charlie Gard, who suffers from a rare genetic condition and has brain damage, to undergo a therapy trial.
Specialists at Great Ormond Street Hospital in London, where Charlie is being cared for, say therapy proposed by a doctor in America is experimental and will not help.
They say life support treatment should stop.
A High Court judge in April ruled against a trip to America and in favour of Great Ormond Street doctors.
Mr Justice Francis concluded that life support treatment should end and said Charlie should be allowed to die with dignity.
Three Court of Appeal judges upheld that ruling in May.
A panel of three Supreme Court justices on Thursday dismissed the couple's latest challenge after a hearing in London.
But justices said doctors should continue treating Charlie for 24 hours to give judges in Strasbourg, France, time to look at the case.
Ms Yates screamed as Supreme Court justices announced their decision.
Charlie's mother left the hearing in tears and broke down outside the court room.
"How can they do this to us?" she yelled.
"They are lying. Why don't they tell the truth?"
Mr Justice Francis had made a ruling on April 11 after a trial in the Family Division of the High Court in London.
He heard that Charlie, who was born on August 4 last year, had a form of mitochondrial disease, a condition which causes progressive muscle weakness and brain damage.
Specialists in the USA have offered a therapy called nucleoside.
Charlie's parents, who are in their 30s and come from Bedfont, west London, have appealed for money on a GoFundMe page to cover doctors' bills in America.
They reached a £1.2 million target before the High Court trial.
People are continuing to donate and the fund has now topped £1.3 million.
Mr Justice Francis said Great Ormond Street doctors had considered the experimental treatment, but decided it would not help Charlie.
He said the case had never been ''about money''.
A panel of three Supreme Court justices analysed the couple's case at a hearing in London.
Justices considered preliminary arguments and were asked to decide whether to give the go-ahead for a full appeal hearing.
Lady Hale, Deputy President of the Supreme Court and the most senior justice on the panel, said justices had decided to block the couple's appeal bid.
She said any judge was bound to have the utmost sympathy with Charlie's parents.
But she said Mr Justice Francis had made decisions he was entitled to make.
A Great Ormond Street spokeswoman said the thoughts of staff were with Charlie and his parents.
"This is a very sad day for Charlie's parents and family," she said.
"It is never easy when medical and judicial opinion goes against the wishes of the parents but our first responsibility at Great Ormond Street Hospital remains to put the interests of the child first and foremost.
"It is also hugely difficult for any clinically-trained professional to be asked to treat a child who has no chance of survival or even improvement in his quality of life.
"We are led by the legal process and when the time comes for a change in treatment, we will support the parents in every way that we can, aiding them through next steps. This would normally take place over at least a number of days.
"For now, our priority is to ensure Charlie remains well cared for and to offer our support to Charlie's devoted parents at this distressing time."
Lade Hale had told the court when dismissing the couple's challenge.
"Any court is bound to feel utmost sympathy for devoted parents who are desperate to explore every possible way of preserving the life of their gravely ill but much-loved baby son," she told the court.
"As parents we would all want to do the same. And this case is unusual in that the parents are not asking the hospital to provide or continue treatment at public expense.
"It is the hospital which has asked for permission to withdraw artificial ventilation and provide only palliative care.
"Charlie's parents are asking that the hospital continue to keep Charlie alive by artificial means until they can take him to the United States for the treatment which has been offered there and for which they have raised the funds to pay.
"How, they argue, can the hospital try to prevent them from transferring the care of their son to another team?"
She added: "However, as judges, and not as parents, we are concerned only with the legal position.
"We are bound to accept the factual findings of the trial judge, who has heard the evidence, including the evidence of the doctor in the USA who is prepared to offer treatment, and the judge found that further treatment would be futile.
"The legal test which he applied was whether further treatment would be in Charlie's best interests and in his order he expressly found that it would not be."