The notion that police would be allowed to take and retain DNA from children was controversial from the start but the prospect that it could potentially help officers catch repeat offenders who commit violent or sexual offenders tipped the scales in favour of allowing it to be done.

News that the number of under-18s on the national DNA database has more than tripled in the last three years, however, raises the question of whether the careful balance that must always be struck between preserving civil liberties and tackling crime has been lost.

There are more than 35,000 children on the DNA database, with 251 records from children of 13 and under; two are of 10-year-olds. Some of those whose DNA is on the database have been arrested but have not been found guilty of any crime.

The key concern of politicians and children's campaigners is that this practice brands children as potential criminals. Children's problematic behaviour is often a manifestation of deeper problems and needs and, with help, it can often be brought to an end. The charity Children 1st points out that children are far more unlikely than adults to reoffend if given the right help and support. The stigma of being labelled as a potential offender or reoffender in the eyes of the police and possibly their peer group is unhealthy and unhelpful for a child who just needs help.

If police officers wish to keep this power, then they must put forward clear evidence to show that holding the DNA of children actually helps solve crimes and that the rising numbers of samples being retained are in proportion to the number of crimes being solved.

The saving grace of the legislation passed in 2010 is that records may only be held for up to three years; police may then request an extension in specific cases for another two years. This is a lower retention period than in England and Wales, and rightly so. But three years is a very long time in the life of a child. It is in no-one's interests that a child develops an ingrained criminal identity at a young age. With this in mind, the way children's DNA is retained and used must be kept under close scrutiny by politicians, and the possibility must be kept open of tightening the rules if the careful balance between individual rights and tackling crime is lost.