A NEW watchdog is needed to oversee the burgeoning use of biometric data such as DNA and facial imagery by Police Scotland, an independent expert group has said. The advisory group recommended a new code of practice on the “acquisition, retention, use and disposal of biometric data”, which is defined as "any physical, biological, physiological or behavioural data, derived from human subjects” which could identify individuals.

A new independent Scottish Biometrics Commissioner would be needed to monitor the police’s compliance with the code, it said.

There should also be a review of the 1995 legal rules on data retention to consider questions of proportionality and necessity, and a “national debate” about biometric data.

The SNP government backed the thrust of the report and a Commissioner “in principle”, but said it would need to consult Holyrood’s authorities about the necessary legislative steps.

The group was set up last year after criticism over the way the single force retained custody images of people charged but never convicted of a crime.

Police Scotland hold more than 1m of these and retain them for up to seven years.

The report said: “Police Scotland has no technical means of understanding how many people these records relate to and has no automated means of establishing how many custody images it holds of people who have not been convicted of any offence.”

The force held 432,888 people's fingerprints and photos of 362,348 individuals in its criminal history computer as of August 2017.

As of December, Police Scotland also held 332,213 criminal justice DNA samples.

Fingerprints and DNA from those convicted of a single criminal offence can currently be retained indefinitely, regardless of gravity.

Fingerprints and DNA from those arrested but not convicted must be destroyed immediately with exceptions for certain sexual or violent offences.

Human rights lawyer John Scott QC, the chair of the advisory group, said it had been 10 years since the Scottish Government reviewed the regulation of DNA and fingerprints.

He said: “Since then, there have been continuing developments in biometric technologies.

“This review offers the opportunity to take account of these and future developments and develop a framework for the regulation of all policing aspects of biometric data, reflecting the significance of such data in policing as well as all ethical and human rights considerations.”

Justice Secretary Michael Matheson said: “The Scottish Government accepts the Group’s report and the thrust of its recommendations. While the creation of a new Biometrics Commissioner to monitor compliance with a new code will require careful consideration and discussions with the parliamentary authorities, it is one that we accept in principle.

“The public should continue to have confidence in how their information is held and I hope that the publication of this report will kick-start a wider debate on biometric data and how it is best used to help keep our communities safe.”

LibDem MSP Liam McArthur, whose party has been pushing for tougher rules on biometric data for three years, said the report underlined the need for urgent reform.

He said: “Biometric technologies which draw on our personal characteristic are becoming an ever greater part of all our lives. They are emerging at an incredible rate but we need to ensure our laws keep up and that people's rights aren't infringed.

“That is why we need regulate the use of existing technologies and future proof them to cover those systems that won't have even been invented yet.

"It shouldn't have taken the Scottish Government three years to get to this point. Ministers must immediately get on with preparing the necessary changes to the law."

Police Scotland Assistant Chief Constable Gillian MacDonald said: “Biometric data, particularly DNA, fingerprints and photographs, is a critical tool in the investigation and prevention of crime. We recognise the importance of ensuring that the public has trust and confidence in the procedures which govern its use.

“Any endeavour to strengthen the legislative framework and provide a balance between keeping the public safe from harm whilst ensuring the appropriate consideration of human rights and ethics is welcomed.

“Police Scotland, having been a key contributor to the work of the Biometrics Independent Advisory Group, supports all of the recommendations."