The police themselves have said* that the number of times that a sample from the database has been used to solve a crime is relatively low, but ‘unfortunately’ they don’t break the figures down this way in their records, so they can’t give an accurate ratio or percentage for this particular point.

* I admit it, I read this somewhere a couple of months ago and I can’t find the reference now. If anybody finds it I’d really appreciate the link, thanks.

I have made no attempt to defend the existing system in the UK I merely highlighted that such material has proved successful in crime detection – according to this item:

DNA is successfully obtained at less than 1 per cent of crime scenes. But according to the Government, it is still having a significant impact, with the presence of DNA sharply increasing the chances of solving a crime. The crime detection rate last year was 26 per cent; where DNA evidence existed it rose to 40 per cent.

Recent advances in DNA technology have also allowed police to reopen their investigations into scores of unsolved “cold cases”. This work, Operation Advance, has so far led to 21 convictions with sentences handed out to date totalling more than 100 years as well as three life terms. Those who have been tracked down include James Lloyd, the South Yorkshire “shoe rapist”, who was convicted for sex attacks in the 1980s after his sister gave a DNA sample when she was stopped over a driving offence.

Police also argue that the database is a useful tool for ruling out the innocent from their inquiries.
http://www.independent.co.uk/news/uk/crime/the-big-question-what-is-the-dna-database-and-why-do-we-have-so-many-people-on-it-422532.html

As I mention above I am very pleased to hear that the present arrangements are being reviewed and I do not dispute that the iniquities highlighted in your post – obviously, these need to be addresses as soon as possible.

“Holding DNA is not (of itself) synonymous with accusations of guilt”

Well it is, otherwise why hang on to an innocent person’s DNA?

There are, as I understand it, 11 loci (or Short Tandem Repeats, STRs) of the DNA on the database of which one is a gender marker. The claim is that 2 unrelated individuals matching has a probability of about 1 in 1 billion.

Unless you have contaminated samples, of course. Which has happened: http://www.latimes.com/news/printedition/front/la-me-dna26-2008dec26,0,7018280,full.story AND http://scotlandonsunday.scotsman.com/rapeandthelegalsystem/DNA-flaws-set-to-clear.2481141.jp

“…if a serial rapist … is brought to book because of held DNA material…”

Whilst rapists become aware of DNA evidence, they destroy it by pouring acid into the victim. But, hey, at least we have a database!

And why is it the database holds details of 37% of black men but fewer than 10% of white men? Is a serial rapist more likely to be black? And who’s to say it won’t be used for nefarious purposes? For example, in early 2007, five civil servants were arrested for allegedly stealing DNA information from the database. And it costs some £60m a year to run. For catching other than serious crimes is this cost effective?

And given the (well massaged) figures from the government – which seem to bear little relation to innocent persons DNA – I’m not convinced about this database at all.

In Lee’s scenario an innocent person might end up doing jail time because of a sneeze. Perhaps there is also an implied suggestion that we can never fully trust the authorities to manage this type of complex data, either ethically or competently.

On the other hand if a serial rapist, or potential murderer, is brought to book because of held DNA material then I think we have to think carefully before throwing the baby out with the bath water.

On balance the ECHR accepts there IS a case for retention of DNA – but criticises the UK because of timeframe and scope (i.e. DNA is held for too many people and for too long).

As I understand it the Home Secretary has already agreed to review arrangements and it might be that we end up with the kind of system that exists in Scotland which imposes a 3 year limit (in the main) on held DNA because most of the evidence suggests that re-offenders are likely to strike again within this sort of timescale.

That was pretty much what I was trying to say, but I failed on succinctness. I often do.

The problem is that innocent people are being kept on the database for an arbitrary period of years.

The other problem is that a forensic DNA match is in very nearly all non-TV instances a partial. I.e. it could match more than one person in a population of 60 million. Put those two things together and it adds up to a problem.

Or, you could look at it the other way around. Do you trust the government to only let the cops look at your records? [1] Or are we going to find council employees using Terrorism legislation and DNA matching to identify who stuck gum under the pews at St. Botolphs?

[1] Which begs the question do you trust the police?

Dear Diana Johnson,

Yours sincerely, Daniel