A Merseyside school was ordered to pay compensation to a pupil who fractured his skull after jumping on a skylight which broke. The court awarded damages, yet to be decided, to David Davies, 16, after he fell 20ft through the roof of Brookfield high in Kirby in 1995.
Despite admitting that the 12-year-old pupil was 60 per cent responsible for the accident the judge ruled that the school's failure to cover the skylights with guards made it liable.
NUT solicitor Graham Clayton said: "This is not a new principle of law, but it is at the extreme of this kind of case. Local authorities have a duty to keep school buildings in a sufficient state of repair to take account of the fact that children do odd things."
Whether they are pupils, children playing in the grounds or vandals wrecking the building was immaterial, Mr Clayton said.
Mr Justice Morison said: "A careful parent would have foreseen the danger of having children on a roof with skylights and could be expected to ensure that they were solid enough to cope with heavy use."
Although Brookfield had told pupils not to go on the roof, it was still responsible, he said.
David Hart, general secretary of the National Association of Head Teachers, said: "The judge is placing upon schools a level of care which may be difficult if not impossible for all schools to match."
David Davies's mother, Yvonne McGuiness, brought the action against Knowsley council. A spokesman said: "Knowsley's education department contested the case as it has always made clear to pupils that climbing on roofs can be potentially dangerous and is acting against school rules."