Kathleen Marshall discovered she was at the centre of a political controversy last week when she pulled up at traffic lights and glanced at the newspaper being read in a neighbouring car. There was her picture below the headline: “Outrage as child czar opposes teen sex laws.”

The story referred to comments Marshall posted on her website in response to a consultation clarifying the law on rape and other sexual offences. Scotland's first commissioner for children and young people wrote: “I welcome the proposals to reconfigure the law on sexual offences involving children. It is right that there should be an age below which there can be absolutely no excuses or defences and such activity is recognised as simply wrong (although I make some qualification as regards children under 13). Setting that age at 13 seems reasonable.”

These Scottish Law Commission recommendations effectively advocate decriminalisation. The commission, whose proposals are expected to be rejected by the Scottish government, says children under 16 should not be prosecuted for consenting sexual activity with other children aged above 13, but may be referred to the Children's Panel where appropriate.

There are concerns about the permissive message this sends out to young people and the dangers of, say, a boy nearing his 16th birthday seducing a girl who has just turned 13. This is why Marshall's backing of the recommendations caused such upset.

Sitting in her office a few days later, however, she says she does not support a lowering of the age of consent.

“I would be horrified if someone said the age of consent should be lowered to 13. What I am saying is that I cautiously welcome proposals to take a different approach to consensual sexual activity between young people.

“It is not what we want for our children and I am not saying early sexual activity is good, but if your 15-year-old son is having a sexual relationship with his 15-year-old girlfriend, do you want him to be prosecuted? To have a criminal record? The current law says the boy is breaking the law.”

Marshall says she recognises that consensual sex under 16 can be damaging and exploitative, which is why she approves of referral to the Children's Panel where appropriate.

She acknowledges that her previous stance, in support of the status quo because the police very seldom prosecute boys for having sex with their girlfriends, was inconsistent with the existing law. “My view was that if the law ain't broke, don't fix it,” she says. Now, however, she feels the issue has been raised and it would be wrong for her not to address it.

“I felt the law was introduced to protect 13- to 16-year-olds, but is it appropriate to use these laws to punish children? I want to make clear that I am not condoning sexual relationships among children that age and I am not saying it is an acceptable norm.”

When Marshall was appointed children's commissioner by the former first minister Jack McConnell in 2004, her role was to review the law, policy and practice in relation to young people. The Scottish government had promised to put children at the heart of every piece of legislation and it was her job to ensure their views were taken into account. She came in for criticism soon after she started her £72,000-a-year job when it emerged that she planned to spend an estimated £375,000 of taxpayers' money to find out what children want.

Given that she was once director of the Scottish Child Law Centre and has worked with children for 20 years, critics argued that she should come to the role armed with that knowledge.

Today Marshall, who has one year to run on her current contract, still has her critics. With a staff of 16 and an annual budget of more than £1m, the commissioner still seems to be asking more questions than she answers. Her time in a quango has left her conversation peppered with jargon about best practice, proactive strategies and children's rights impact assessments. When it comes to explaining what the commission has actually achieved, however, this language obscures more than it enlightens.

So, in simple terms, what did the initial research reveal about what children want? “The No1 response was that children wanted more things to do,” she says. “In second place was the issue of bullying and in third they wanted safer streets. More than 50% of the responses raised issues of fear among young people.

“Bullying is a huge issue. It has got much more complex with cyber-bullying online and by text. There is the potential for bullies to exercise power not just at school but in the home, where they should feel safe.”

When it comes to sorting out the problem, however, the children's commissioner doesn't have the answers. She says the issue is being addressed by the Respect Me campaign established by the previous government to tackle bullying.

Similarly, with the complaint about lack of play facilities, she refers me to Play Scotland, a charity set up in 1998 and funded by the Scottish government that aims to create more play opportunities. The commissioner's office, meanwhile, has embarked on more research to pinpoint what is available for children by asking them to fill in a detective-style quiz about facilities in their area.

Once the results are in, Marshall hopes to establish a play strategy for Scotland, a faintly ridiculous phrase that she acknowledges provokes scepticism. “I brought it up on Newsnight Scotland and got a fairly incredulous response from Gordon Brewer,” she admits. It also sounds far too bureaucratic to be any fun.

“I want to make sure play areas are factored into planning decisions,” says Marshall. “It will take into account some of the fears that parents have about letting their children out to play.”

With an overarching remit to safeguard the rights of children in Scotland, the commissioner's practical responsibilities seem less clear. Is she, for example, involved in the fight to reduce obesity among young people? Her response is vague. She goes on to argue that an increase in things to do through play will contribute to more exercise and better health, adding that she has also supported the campaign for healthier school meals.

A scheme to introduce children's juries in the Borders, where youngsters as young as 11 accused of minor crimes such as vandalism will be judged by their peers, is another matter that falls outside her jurisdiction. Marshall, a lawyer, has heard of the plan but isn't familiar with the detail.

What about the SNP government - is it as committed as its predecessor to keeping children at the heart of legislation? “More could be done to make that a practical reality,” she says. “I have recommended that the government introduce a children's rights impact assessment on everything they do, like they have with human rights law, and that is being trialled in some areas. I think it could be used more widely. The government seems positively disposed towards the idea.”

Despite the criticisms that can be levelled, the commisioner has tackled issues of importance to children including a call for young people in care to be allowed to stay in the system until they are 18, a report highlighting the rights of children of prisoners and a study into the handling and moving of disabled children.

The commissioner also spoke out on behalf of the children of asylum seekers detained at Dungavel centre. More recently, she condemned “mosquito” devices, the high-pitched alarms used by some shopkeepers to disperse groups of teenagers.

Marshall, a mother of three grown-up children, strives to meet as many young people as possible in the course of her job and she will continue to consult the young people in whose name she is employed.

“There is so much work to be done,” she says. “Young people just want to feel safe and protected. We need to help them do that.”

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