The security firm which delayed the appeal of Banbury mother Patricia Amos by more than three hours escaped with a warning.
Judge Peter Crawford said he was astonished by the casual way in which Securicor Custodial Services brought prisoners to court.
He said no-one was in charge and the handling of prisoners' was scandalous. He accused the company of trying to perform its duties with inadequate resources.
Amos, who was appealing against a 60-day jail sentence for failing to send her two daughters to school, was due to appear at Oxford Crown Court at 9.45am.
The escort van left Holloway Prison at 9.06am, called at Guildford court and arrived in Oxford at 1pm. The judge and two magistrates were kept waiting until the case could start at 2pm. Mrs Amos's sentence was cut to 28 days and she was released immediately.
The judge said yesterday: "I take the view that she was unlawfully detained and she has a cause of action for damages."
Brian Gallagher, for Securicor, gave an unreserved apology and admitted the company had "dropped the ball". He blamed a breakdown of communication and planning.
The judge said he had considered contempt of court proceedings or referring the case to the Attorney General, but on reflection he had decided to take no further action.
He said he expected the Home Office, which controls the firm's contract, to look seriously at the matter.
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