A teacher who was arrested but not prosecuted after being accused of hitting a child twice with a ruler yesterday won a legal battle against police to have her fingerprints, DNA sample and photograph destroyed.

Philippa Jones, from Kings Norton, Birmingham, was also awarded ?250 damages from the chief constable of West Midlands Police, and her legal costs.

Miss Jones launched the High Court action to establish that the taking of her fingerprints and DNA, at a point after the Crown Prosecution Service had decided not to prosecute, was unlawful. She had also claimed damages for false imprisonment and assault.

Mr Justice Wilkie approved a settlement in which the police agreed to destroy the fingerprints, DNA and photograph and pay damages.

The case came to court at a time of concern about the retention on the national DNA database of thousands of samples from people, including juveniles, who have not been convicted.

However, the Home Office and the Association of Chief Police Officers played down the significance of the case.

Sources said that it centred on the taking of samples in a period of unlawful detention - a breach of police procedures - and did not interfere with the powers to take lawful samples or the chief constable's discretion to erase them.

Observers said, however, that it highlighted the legal limits on the powers available to police and underlined the need for samples to be taken in lawful circumstances under the Police and Criminal Evidence Act.

Miss Jones, a supply teacher in the West Midlands, was arrested on June 14, 2005, and taken to Kings Norton police station following an allegation by an eight-year-old child that she had hit him twice with a ruler.

She "strenuously denied" the allegation, and at 2.20pm on that day the Crown Prosecution Service decided not to prosecute.

However, at 2.27pm, despite representations by her solicitor that she ought to be released, the police insisted on taking her photograph, fingerprints and a DNA sample. According to a statement presented to the court by her solicitors, the police went ahead even though Miss Jones's lawyer had told them that their action was "inappropriate" as the CPS had decided not to prosecute.