Transcript for The fight for baby Charlie Gard
here tonight with a wrenching fight over an 11-month old baby boy, a fight that's brought in everyone from the president to the pope. Charlie guard is critically ill and doctors in England say there's nothing to be done but his parents say they're blocked from trying a experimental treatment from an American doctor. Here's Lindsey Janice. Reporter: 2016, best day of our lives. Day Charlie was born. It's been a battle for Connie and Chris. We're going to fight for him. A battle not just against the disease Rav aging their son's body but against their own government. We can't even take our own son home to die. This is their 11 month old son who doctors say he cannot see, hear, move or cry born with a rare, genetic disease that left himself earseverely brain damaged. His parents live in the uk and want him to under go experimental treatment in the U.S. But courts say his condition is too grave and it would be cruel to keep him alive. We feel it should be up to the parents to decide to give him a chance at night. It ignited a fierce debate over hospital's right to treat its patient as it sees fit and parents right to decide for their child. It's unimaginable position for anyone to be in. The pope extending support. And president trump tweeting if we could help little Charlie guard we'd be delight led to do so. We're there 24 hours a day, if we were suffering in pain we couldn't sit. In the uk it is not uncommon for courts to side with hospitals over parents. The doctors argument is this child is suffering. I haven't seen any evidence the child is suffering. Now a sign of hope for the family. We're quitele happy with the outcome today. The British court giving new support it for the experimental treatment could in fact help their son. This U.S. Doctor said there could be 10% chance his muscle strength could improve. Today the doctor arriving by Charlie's side to assess if anything can be done. We can see a variety of symptoms. Patients develop muscle weakness, nervous damage, seizures. Doctor is a specialist in this disease. The earlier you show the symptoms the more severe the outcome for the patient. Dr. Has tried this before. Five years ago with a family here in Baltimore. Their son, art Jr. Was 14 months old when they noticed something was wrong. I had a strong intuition that something was wrong. I was right. At his worst point, how bad was it? He was lying in a hospital bed and most he could do sometimes is move his head a little bit to many say no. Couldn't even shed steetears. He had multiple practice yours in legs and arms and couldn't cry. Their son diagnosed with a similar syndrome and like Charlie doctors told his parents there was little chance for survival. You were told there was no home and no cure. Right that it was terminal and average age for these children was three years old. He was basically dieing on us. But what his parents call a miracle appeared in the form of a pioneering experimental treatment and art would be the first child in the U.S. To get the treatment. They administered first trial at Johns Hopkins hospital. We were very lucky to his geneticist who were like there's hope for this, let's go ahead and try. I will never in my life forget how special that woman is. Little art went from being on the brink of death to gaining some motor functions back. The iPad I would have to grab his hand and arm and push the buttons and you can see, he's in an odd position, he didn't have the tray, he knows the code and enters it and off he goes to YouTube. And he can say iPad. He says mommy, daddy. He's a determined little boy. A movie on his iPad calling out to his parents. The small joys of childhood they never thought art Jr. Could have. Even with all of his progress art and Olga are quick to know the treatment are not a cure. He has six alarms and whenever we hear one of the alarms we both jump up. There you go. I wonder if he kicked it off. In the middle of our interview a feeding break that accompanies three to four treatments he gets every day. Unfortunately right now there are no therapies that we know of that can could stop a progression of mitochondria disease and doctors say he will not get better and that this treatment will make him suffer more. I say to them to educate themselves. See how these treatments will create the enzymes that little Charlie needs so he could get stronger like my son. This family says they'd rather have art Jr. Like he is never not at all. When baby Charlie's doctor say this treatment would only cause him more suffering, you laugh. You don't believe that that's the case. Of course not. I mean, it hasn't caused our son suffering. They say Charlie deserves the same chance their son was able to get. It's difficult sometimes to put yourself in that place. Ifour own child, there was one little hope, wouldn't you do anything, anything to say that baby? I'm confident that Charlie may get a chance now. But the attention tonight is on Charlie's brain condition, can the treatment help to reverse the disease or is there already too much damage. Their assessment is expected to be completed by Thursday. He's got nothing to lose. We know we've done, even if it doesn't work, which I think it will, we know we've done everything that we can for him. Tonight as baby Charlie is kept alive by a ventilator his fate rests in the hands of a British judge. How do you deal with this deadline hanging over you? What other option do we hav Charlie's our son and we love him and we'll fight to the bitter end for him.
This transcript has been automatically generated and may not be 100% accurate.