Six-year-old Jack Adcock died at the Leicester Royal Infirmary - the victim of a series of mistakes, missed chances and failings.
He died from sepsis in February 2011, and his parents have campaigned on his behalf ever since.
Hadiza Bawa-Garba was the doctor in charge of paediatric care that night.
She was found guilty of gross negligence manslaughter and eventually struck off.
But that's been challenged, with her supporters arguing that she was working under extreme pressure; has a first class degree; and many years of service remaining to patients.
Last month, outside court, she had this message for Jack's family.
But Jack Adcock's parents want Hadiza Bawa-Garba to be prevented from ever working again.
I hope to God they keep her struck off, I hope to God she never works in the UK ever again, and I tell you now if she is reinstated I will make sure there is a public uproar - trust me.
Today the Court of Appeal is due to decide between a mum seeking justice for her son, and a medical professional who argues her career shouldn't be over - after mistakes made while working under extreme pressure.