Playing rugby could have been sufficient to spark off the psychological trauma a schoolboy claims was caused by punishment by his teacher, a court heard.
Dr William Green said yesterday that Edmond Cheung Yee-mong's condition could have been brought about by the sort of confrontation that children normally face at school.
He said incidents which occurred during games of mini-rugby, for example, 'could easily have precipitated the events' in question.
He said Edmond, now 13, was already suffering from anxiety when manhandled in class by teacher Ko Hing-biu in April 1991.
The boy is seeking $9 million damages from Mr Ko and the Gloria English School as a result of severe psychological trauma he claims to have suffered as a result of the incident.
Dr Green said Edmond was already suffering from obsessive conduct disorder.
This was then triggered by the classroom incident in which Mr Ko attempted to force Edmond's hand over his mouth while trying to silence a noisy class, he said.
But Dr Green said the disorder could have been sparked off by the kind of everyday contact experienced by children, and not by the classroom incident alone.
He told the court: 'It has to be physical contact which is more than just the normal brushing against someone in the street, for example.
'It has to be unwanted contact which would amount to a push or a shove or more than that.' Neville Sarony QC, for Edmond's family, disputed that Edmond was suffering from anxiety before the incident with Mr Ko.
He also challenged Dr Green's view that the manhandling was not serious enough to cause the boy post-traumatic stress disorder.
But the doctor, a former army medical officer, agreed that if a corporal treated new recruits in the same way to enforce his discipline he would regard it as unacceptable.
The court heard that Edmond suffered a neck injury as a result of his treatment at the hands of Mr Ko.
He now fears being touched by anyone, sobs for long periods and has attempted suicide.
The hearing, before Mr Justice Conrad Seagroatt, will continue after Easter.