Police powers of stop and search are firmly on the agenda in Scotland, thanks to the report from Edinburgh University that has shed light on some surprising figures and highlighted practice which is concerning.

I believe that stop and search is a legitimate police power that assists in the proper exercise of their duties. Because it involves intrusion into someone's privacy, it is subject to certain procedural requirements to ensure that a person's human rights are upheld. This is, quite rightly in my view, the position in the use of statutory stop and search.

However, in Scotland the police also have a power of non-statutory stop and search and it is the exercise of this power that raises concerns about potential infringements of rights. The widespread use of non-statutory stop and search has been the main factor in a sharp increase in the figures; it accounts for more than 70% of instances.

The increases are most evident in the cases of children and young people, who may give their consent to being searched without sufficient information or awareness of their rights. The result is that tens of thousands of children and young people have been searched, most without statutory authority.

In the former Strathclyde region, there were more searches carried out on 16-year-olds than there are children of that age (1406 searches for every 1000 16-year-olds). Statistics like these ring alarm bells because they mean that some young people are being searched many times.

The Edinburgh Study of Youth Transitions and Crime, a major longitudinal study that has influenced youth justice in Scotland, has identified the potential negative impact of "adversarial police contact" such as stop and search.

This research has demonstrated that such contact may in itself contribute to youth crime. It would seem to indicate that widespread use of stop and search could have the effect of creating a pool of "usual suspects" perpetuated by police practice. So, while the Edinburgh study is informing Scotland's approach to youth justice, the figures on police use of stop and search stand in stark contrast.

Scotland has witnessed a welcome reduction in crime, including violent crime. But we know that interpreting crime figures is a complex issue.

Police Scotland and the Scottish Government claim that the drop in crime rates is directly linked to the success of stop and search, but no robust research has been conducted.

Without the evidence, it is not possible to assess how effective it may be, nor whether it is more effective than other approaches that involve a lesser degree of interference with children's rights.

It is worth noting that, in Glasgow during the same period covered by the stop-and-search figures, there was the Community Initiative to Reduce Violence (CIRV). This was credited with having a significant impact on gang related behaviour and consequent reductions in violent crime.

While the former Strathclyde region has by far and away the highest levels of stop and search, it appears that Police Scotland might extend the approach nationally, presumably with a similar emphasis on the stop and search of children and young people. The interaction between police and young people is vitally important. But I fear that we risk alienating our young people through the practice of stop and search on the scale we are witnessing.

As Police Scotland continues to develop a national approach to policing, we must we heed the lessons from England where Her Majesty's Inspectorate of Constabulary recently criticised excessive use of stop and search and its disproportionate use for particular groups , in this instance the black community.

On any reading, it is clear that young people are being targeted and there will be times when their rights are being infringed.

In a the country that claims to be committed to children's rights and wants to be the best country in the world in which to grow up, this needs to be addressed urgently.