A 14-year-old boy at a Somerset school was accused of squeezing the breasts of two girls aged 14 and 15 (neither the school nor any of those involved can be named for legal reasons). The headteacher suspended the boy for three days, offered him counselling and told him to take lessons in his (the head's) room for a short time after he returned to school.
But the girls' mothers were not satisfied and reported the incident to Avon and Somerset police, who investigated and recommended a formal caution. The mothers persisted and the case went to court where the boy admitted two offences of indecent assault and received a one-month conditional discharge.
After the hearing, the head said: "I have been a headteacher for nine years and this is the first time that I have had an incident of school-based behaviour taken to court. We had dealt with it to our satisfaction and that of the governors. The boy was punished and the girls felt protected."
He said there was a nine-month delay between the incident and the court case which made it difficult for the school to return to normal. There was also an argument the boy had been punished twice.
"In a mixed school, boys and girls will make mistakes," he said. "It is my job to make sure that anti-social mistakes are corrected and we educate them on how to deal with each other."
An Avon and Somerset police spokesman said: "We are duty bound to investigate a complaint, consider the evidence and prosecute on that basis."
David Hart, general secretary of the National Association of Head Teachers, said heads faced difficult decisions when dealing with pupil behaviour which could be subject to criminal prosecution.
"They have to make a judgment whether a complaint can be adequately dealt with as an internal disciplinary matter, or whether the police should be called in. A head may consider his disciplinary action appropriate, but cannot prevent parents from exercising their legal rights."
But he said that schools should make their position clear on discipline, codes of conduct and sanctions. "Although you cannot enforce these by law, there are those who argue that parents could be asked to sign an acknowledgement that they accept the school's code of conduct and will support its endeavours to ensure it is observed."
Mr Hart said problem pupils raised the wider issue of whether schools should refuse to admit them.
"We are not moving into a selective system by stealth, but we are in a Catch 22 situation. It is a question of whether you admit pupils without making pre-judgments about them, but then find that you cannot cope. Or you reserve the right to rule out pupils with appalling track records."
Margaret Morrissey of the National Council of Parent Teacher Associations said schools should spell out their code of conduct to parents and pupils before they started school.
"If parents want their children to go to these schools they should accept the code of conduct and support the headteacher. I can understand the feelings of the girls' mothers in this case, but I would not have expected them to go to the police on this issue."
Nigel de Gruchy, general secretary of the National Association of Schoolmasters Union of Women Teachers, said the union supported teachers and heads who wanted good standards of behaviour and discipline - "there are many other pupils to consider and we do not want their education disrupted".
But Sandra Horniman of the National Childrens' Homes Action for Children Campaign questioned whether schools treated cases of sexual abuse between pupils seriously enough.
An NCH committee of inquiry on juvenile sexually abusive behaviour recommended that incidents should always be reported to social services or the police for investigation, and that the police should always take action where a young person is believed to have sexually abused another child.