A family court judge has been urged to reveal detail about a case in which a little girl was placed into foster care after being locked in a bedroom.
The youngster - now seven - was living with grandparents in the West Midlands.
They say social workers intervened after she was twice locked in a bedroom in a bid to keep her safe when she started to wander at night.
The couple say Judge Rosalind Bush decided that the youngster should go into council care after a private family court hearing in Wolverhampton.
Former Liberal Democrat MP John Hemming, who campaigns for improvements in the family justice system, says the case has been brought to his attention and troubles him.
"These grandparents think that their granddaughter was taken from their care because she was locked in a bedroom," he said.
"The problem is they don't appear to have had any proper, written explanation from the judge.
"Certainly no judgment has been published.
"This couple have a right to an explanation. For one thing, how can they mount any kind of appeal if they don't understand why the judge has made the decision she has made?
"But there are wider issues at play here.
"Parents should know if a judge has decided that a child must be taken into care because she was locked in a bedroom.
"It's a matter of public interest and a matter of public education.
"I doubt she's the first child to have been locked in a bedroom."
He added: "The judge should publish a ruling - without identifying the child involved - outlining the evidence and explaining her thinking so that people are aware."
Legal advisers representing the couple say they have asked Court of Appeal judges in London to re-open the case and re-analyse evidence.
Earlier this month researchers said people were being left with a ''patchy understanding'' of the family justice system because judges did not consistently following guidance on the publication of case rulings.
Academics at Cardiff University's School of Law and Politics gathered data three years after judicial heads issued guidance following ''secrecy'' complaints.
Researchers analysed more than 800 rulings published in the two years after guidance was issued.
A report said ''only 27 judges and 12 courts'' had sent more than 10 cases to the British and Irish Legal Information Institute website for publication during that period.
Mr Hemming says there were about 25,000 family court cases involving council social services bosses and children in England between 2014 and 2016 but judges published less than 1,000 rulings.