An arresting idea that deserves to be dropped

Once upon a time – nine years ago – there was a Home Secretary called Michael Howard who tried to prove he was tough on crime. He brushed aside thoughtful concerns about the erosion of civil liberties when he proposed lots of new measures that the police said they needed.

One was a plan to set up a database of DNA samples taken from everyone arrested for a recordable offence, regardless of whether they were later charged. Like many other illiberal measures, he could not get it through the House of Lords. And, like other measures such as curbs on the right to silence or to a jury trial, it was then taken up by Labour Home Secretaries. Jack Straw proposed it two years ago, but did not do it. Instead, it seemed the judges might do it for him when the courts ruled that the police could keep DNA samples from anyone charged even if they were acquitted. But David Blunkett still wants to go further.

If the objections to his plan seem abstract, consider this: when police officers were asked to provide tissue samples for a database to eliminate them from enquiries, nearly half refused. They understood instinctively what civil libertarians have great difficulty persuading a crime-obsessed nation it ought to care about. They knew that the state should only collect information for immediate and necessary purposes. They knew that information in a database might leak to other agencies wanting to test for drugs or paternity or congenital illnesses.

Of course, DNA testing is a breakthrough in linking suspects to crimes, and we should welcome its wider use in securing convictions for serious offences that might otherwise never have been solved. But police officers also know it is fallible.

There is a further important objection that does not apply to the police. Unless the database covers the entire population, simply being on it – having been arrested but not necessarily charged, let alone convicted – undermines the presumption of innocence that is a cornerstone of liberty. If 40,000 police officers said no, how much more strongly should the rest of us feel about it? If Mr Blunkett does not drop this plan, we must once again look to the House of Lords to block it.