Common sense, they say, is a large part of the law but it seems to desert courts when they are invited to overrule school discipline. Last Friday a Christchurch secondary school, St Bede's College, took drastic action against two of its rowing team who rode a baggage carousel at Auckland Airport into the secure area. Their coach, who had not seen the incident, reported it to the college and the rector ordered them home.

The penalty may have been harsh for what was a stupid prank. The boys were let off with a warning by airport security officers and the police. But the school's punishment was in line with a code of conduct signed by the rowing team and their parents before the team left for Lake Karapiro to compete in the Maadi Cup. The rowers agreed to comply with all instructions, school rules and laws and accepted they may be sent home for a serious breach. The parents had signed a consent to that effect.

But when the parents of the carousel riders heard their sons were out of the premier school rowing competition, they consulted a lawyer. The school's rector, deputy principal and legal adviser went north on Sunday, spoke to one of the litigants and stuck by the decision.

On Monday the parents went to the High Court for an interim injunction against the school and succeeded. Judge Rachel Dunningham decided the disciplinary action might be out of proportion to the misconduct and, pending a full hearing, the pair should be allowed to compete.

Since the event would be over before the High Court could review the school's order, she decided the boys stood to suffer the greater harm in the interim. The school could always impose a later punishment if its decision last Friday was found not to breach natural justice.

But the "harm" to the pupils was their exclusion from a sporting event. Their parents said their sons had put in countless hours of training over many months to get the chance to row in the Maadi Cup. Their absence would weaken the school's crew, punishing all of them, and would prevent the pranksters from being selected for higher honours. One of the pair had been a South Island age group representative and had high hopes the Maadi Cup would put him in trials to represent New Zealand at the Junior World Championships.

The school was prepared to do that harm in order to uphold its rules, standards and reputation. It does not want pupils on school trips disgracing its uniform in airport terminals or anywhere else. It regarded behaviour that warranted a warning from police to be serious misconduct. If it did not enforce the code of conduct in this case it might as well not ask parents and pupils to sign it in future.

The court treated the case as though it was an academic suspension requiring a quasi-judicial procedure.

To place the same requirements before pupils can be sent home from a school trip is new and disturbing. It is time the law gave schools more leeway. They are dealing with immaturity and their task is hard enough.