Local authority bosses have come under fire from two of England's most senior judges after deciding not to participate in a Court of Appeal hearing relating to the welfare of two children in an attempt to save taxpayers' money.
One judge said West Sussex County Council had "failed to grasp" what the proper roles of a local authority and the appeal court were.
Another said the council's decision not to instruct lawyers or provide written submissions to the court was "quite astonishing".
Lord Justice McCombe and Sir James Munby - President of the Family Division of the High Court and the most senior family judge in England and Wales - have made their complaints in a written ruling published after an appeal court hearing in London.
Appeal judges said West Sussex council had begun care proceedings after becoming concerned about the welfare of the two children - a four-year-old boy and a three-year-old girl.
The council said a teenage girl alleged that the children's mother and father had sexually abused her - and the authority asked a judge for a ruling on the allegations.
A judge sitting in Brighton County Court found the allegations proved.
The mother and father then asked appeal judges to allow them to challenge that decision.
Sir James, Lord Justice Lewison and Lord Justice McCombe refused to grant the couple permission to appeal at a hearing in April.
And appeal judges were unhappy because the council had not participated in the appeal hearing.
Bosses had provided a "position statement" to the court saying they took a neutral stance and were trying to save public money by not participating.
But Lord Justice McCombe said it was obvious that the presence of the local authority was required and he said the council's approach "fundamentally fails to grasp what were the proper roles of the local authority and of the court".
He said: "Having taken the decision to present these allegations to the judge and having secured findings of fact broadly along the lines that it was seeking below, the least the local authority could have done would have been to attend before the court to ensure that the findings were not disturbed to the potential prejudice of the children in this case, who the authority had been contending were at risk from what they said had happened to another young girl at the hands of these parents.
"Non-participation was not an option."
Sir James said the council had shown a "quite astonishing attitude to the appeal".
He said: "It was neither present nor represented before us. Even more surprisingly it filed a remarkably perfunctory position statement which, without condescending to particulars, simply announced that 'it maintains a neutral stance in relation to the appeal'.
"I do not understand what the local authority thinks 'neutrality' means."
He added: "The local authority... had commenced the proceedings, had decided to make a number of allegations - as it happens very serious allegations - and had succeeded in persuading the judge that most of them were proved. How in the circumstances could the local authority be neutral?
"Had it suddenly become indifferent to the outcome? Surely not. The consequence is that the court was deprived of any assistance by way of response.
"Even if, in order to conserve taxpayers' money (as the position statement said), it was appropriate not to send an advocate to attend the hearing, written submissions resisting the appeal and setting out, even if fairly briefly, why it was being said that the appeal should be rejected would surely have been of assistance."