"I cannot comment on any legal aspects of the case, but I will say that I am very happy right now, and I hope that the surgery is successful," Sarah's lawyer, Steve Harvey, said in a statement.
Sarah had been living at the Children's Hospital of Philadelphia for more than two months and was intubated on June 8. Her mother notified Sarah's Facebook community on Sunday that Sarah was terrified when she wasn't sedated because of the "thick secretions coming out of her lungs and into her throat," causing her to choke and panic.
"It's been terrifying and we have felt so helpless," Murnaghan wrote. "At one point last night I thought we would lose her. I have never felt such sheer panic and terror in my life."
Sarah was born with cystic fibrosis, a genetic condition that affects cells that produce mucus, sweat and digestive fluid. Patients typically suffer so much lung damage that they often go into respiratory failure, which is why Sarah needs a lung transplant to survive.
After spending 18 months on the transplant waiting list, her condition rapidly deteriorated in late May, and her family expected her to be bumped to the top of the adult waiting list because of the severity of her condition, Sarah's aunt, Sarah Ruddock, told ABCNews.com.
"A week went by with nothing, no offers," Ruddock said. "They said, 'Well, you're not at the front of the line. It goes to all adults, and if all the adults turn them down, the lungs go to the kids.'"
Here's how the Under 12 Rule -- which is more like a series of rules -- actually works:
Lung transplant candidates older than 12 are assigned a lung allocation score, or LAS, based on a complex mathematical formula that includes the patient's age and size. For transplant patients younger than 12 -- of which there are 20 nationally compared with about 1,600 adults -- the LAS is not used. Instead, patients are broken into "priority 1" and "priority 2." It's this difference that has been called discriminatory in court.
Children get priority for lungs donated from children younger than 12, but they have to wait for children between 12 and 17 to decline lungs donated from 12- to 17-year-olds before they get a chance at them. Lungs donated by anyone older than 18 are offered to all candidates older than 12, depending on their LAS. Only if all local matching candidates 12 and older decline the adult lungs can they be offered to children within 500 miles of the hospital where the lungs were harvested.
Sarah's lung transplant from an adult donor will be the 11th of its kind since 1987. The last transplant from a donor older than 18 to a child younger than 12 took place a few months ago, according to an OPTN spokesperson. The one before that happened in 2006, when the Under 12 Rule was new.
Because of the court ruling, Sarah has had two transplant database records -- one with her actual birthday and one with a fake 12-year-old birthday -- since last week so she can be considered for child lungs based on her priority level and adult lungs based on her LAS.
Sarah, who dreams of being a singer and a veterinarian, told her parents she wanted to fight for her life but did not know how dire her situation was.
However, Ruddock said she probably knew. Sarah lost her hearing a few weeks ago as a side effect of one of the antibiotics keeping her alive. At bedtime, she began asking her parents if she'd wake up.
At the end of May, Sarah's siblings and cousins gathered to say goodbye to Sarah even though their parents didn't say what was going on, Ruddock said. Doctors told the family that they weren't sure Sarah would survive Memorial Day weekend, but she pulled through.
"She was the little leader in our family. She would always get the little kids to put on a play for us," Ruddock said. "She's a bit of a pistol with a good personality to survive. She's not meek. She's a tough kid."