I'm all in favour of justice being done, and the fact that brothers Stephen and Lee Ainsby have been jailed for kidnapping and raping a teenage girl ten years ago is a good thing. But the manner of their capture raises some concerns.

A couple of years back, Lee Ainsby was arrested for being drunk and disorderly. While under arrest, a DNA sample was taken from him. When it was compared to a database of DNA evidence from unsolved crimes, it matched.

What disturbs me is that the police can take DNA samples from anyone they take into custody, even on a pretty insignificant charge. What next? Will we be expected to give DNA samples when we're pulled over for having a faulty tail light? Furthermore, they are able to keep this on file over the years. In this case it took two years for them to make the match.

There might be a case for checking new DNA against old cases, but there should be a time limit on how long it can be kept. And there is a strong case for setting down tight limits on what kind of offence qualifies for having DNA samples taken.

Otherwise the authorities will build up and retain DNA samples from more and more people over the years, until we effectively acquire a national DNA database by stealth. What then? Will they add our DNA profile to those new identity cards the government wants us all to carry? We need to consider this carefully, not be taken down that road by subterfuge.