The children's watchdog urged MSPs yesterday to delay proposed legislation that would criminalise teenage girls aged 13 to 15 who have sex with boys of the same age.

In written evidence on the Sexual Offences Bill, Kathleen Marshall, Scotland's first Commissioner for Children and Young People, called for the plans to be withdrawn until research was carried out into the likely consequences. Professor Marshall believes sexually active girls may be deterred from seeking medical help if they think that they could end up with a criminal record.

Under the terms of the Sexual Offences Bill, which was published by the Nationalist administration in June, it will become a crime for children between 13 and 15 to have sex. The move aims to eliminate discrimination from the law.

Since at least 1976 it has been possible to charge boys of this age for engaging in sexual activity with girls of the same age. Cases can be referred to the children's hearing system, and show up later in life during disclosure checks, even if the charges are not proven, or, more rarely, prosecuted in an adult court. A girl can be referred to the childrens's hearing system if there is thought to be a threat to her health or wellbeing, but not on the basis of having committed an offence.

The reform represents the opposite of a previous recommendation by the Scottish Law Commission to decriminalise young teenagers who have consensual sex, and refer them instead to a children's reporter where appropriate on welfare grounds. The advice, which would have effectively lowered the age of consent, provoked a storm of protest among parents and church leaders. After the controversy, SNP ministers rejected the suggestion, claiming that it would conflict with safe-sex messages.

In her submission yesterday, Professor Marshall argued that the new legislation could backfire by preventing girls from seeking medical assistance. She wrote: “We need to be certain that the threat of legal punishment and criminalisation does in fact prevent early sexual activity.

“Extending the threat - empty or otherwise - to girls, may have serious negative consequences such as preventing them from seeking help.

“While I recognise that laws applying to sexual behaviour should apply equally to boys and girls, in this case I believe the proposal should be withdrawn until research is done with young people, to understand clearly what measures are effective in discouraging them from early sexual activity.”

In an interview for BBC Scotland, Professor Marshall appealed to parents, asking them to imagine that it was their 15-year-old daughter who needed help: “She's had a relationship with her 15-year-old boyfriend, she's pregnant ... and now it is a criminal offence as well.

“Are you going to get a police investigation? If it goes to the children's hearing [system] on the grounds she has committed an offence is it going to follow her for the rest of her life?”

She added: “If you want to make things equal, let's make things equally better and not equally worse.”

Opinion was divided yesterday over Professor Marshall's stand.

Lynn Jamieson, head of sociology at the University of Edinburgh and an expert on sexual offences, agreed that more research is required before formulating new policy. “If the law criminalised young people who are already in lots of ways disadvantaged, then it doesn't seem a good idea,” she said.

However, John Deighan, parliamentary officer for the Roman Catholic Church, said that the proposals would prevent young people from being exploited. “Do we really want to put young girls into a position where they could be coerced into sex?” he said. That view was echoed by Paul Martin, the Scottish Labour spokesman on community safety. “By decriminalising underage sex we would be sending out the wrong message to our children and also on adults who prey on our children,” he said.

A Scottish government spokesman defended the plan, saying that it had been already made clear “... that this is not about prosecuting children in the adult criminal courts for consensual sexual activity”, and that cases will continue to be referred to the children's panel.

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