Firstly, only about 0.37% of recorded crimes involve DNA detections (and many of those involve other types of evidence as well). No-one is proposing completely stopping the police using DNA evidence, but even if this were to happen, the clear-up rate would drop by 0.37 percentage points at most – and probably by much less, since cases with DNA evidence often also have other types too.

Secondly, putting almost 1 million innocent people on the database hasn’t improved its effectiveness as a crime-fighting tool one jot. Before 2004 only samples from those charged with offences were held, but since then anyone arrested in England and Wales has had their DNA permanently added, even if never charged or convicted. However, despite hundreds of thousands of DNA profiles being retained since 2004 that would otherwise have been deleted, the DNA detection rate has stayed stubbornly constant at 0.37% since 2002. The inescapable conclusion is that retaining the samples of the innocent isn’t helping solve more crime. All those innocent people’s samples could be deleted without reducing the database’s effectiveness at all.

For more data, see Genewatch’s careful analyses, especially “Would 114 murderers have walked away if innocent people’s records were removed from the National DNA Database?”, http://tinyurl.com/6xne7a

Hmmmmmmmm. So a man with a well-paid, prestigious editor’s job – which he would lose in short order if the police did not confide in him – sympathises with the police and their views?

Astonishing.