DNA revisited - part 2

Last week in DNA revisited, part 1, following on from my earlier article, DNA samples from everyone?, I considered some of the objections to a widespread DNA database. Those concerned privacy, liberty and the added worry that a small minority of police officers, or those with access to the database, could misuse the DNA for law and order (or rather the opposite) or commercial purposes.

A common mantra of those supporting the extension of the database, repeated in the same way that the sheep in George Orwell's book Animal Farm (a far more effective and entertaining polemic against totalitarianism than his 1984) bleat "four legs good, two legs bad", is that "the innocent have nothing to fear". That is simply not the case.

DNA evidence is not infallible. It is usually about varying degrees of probability, especially if there is only a partial match. It is all too easy both for the police and experts to get carried away by statistical probability, and consequently juries to be unduly influenced as a result. Remember the statistics as to the likelihood of two cot deaths in Sally Clark's family put at millions to one (a key factor in her original conviction for allegedly killing her child) when in fact the true number was light years from that even before one considered other factors which led to the quashing of her conviction? Some years ago a partial DNA match was relied upon to try and show that a particular person had committed a burglary when his medical condition meant that it would have been physically impossible. The chance of a DNA match being wrong was suggested to be millions to one and yet everyone accepted it was. Had the person not had a condition ruling him out as a suspect, what would you think his chances of acquittal would have been?

All of this is even before one considers the possibilities for misuse of the DNA sample. Although crooked police are a tiny minority, they exist. In a rapidly evolving field, one cannot be certain what might be done with this DNA profiling if it falls into the wrong hands.

Indeed, as our present knowledge is the tip of the iceberg, there is grave concern as to what an authoritarian regime might do with this information. You might be able to assess and selectively leak private details about a person's likely health or propensities. (Bear in mind if we have a national DNA database that DNA could be kept permanently: with scientific advances who can predict say 50 years from now what you might be able to learn or reveal about a person from their DNA?). One does not have to go so far as the doomsday scenario of a Hitler or Stalin to realise that a less malign government could still use this information for other ends. For example, there have already been suggestions that smokers or fat people should have NHS treatment restricted or removed. What if one could profile a "healthy lifestyle" for an individual purely off their DNA? They could then be instructed that they either follow that or have free medical care/social benefits removed from them. When we cannot predict what use might be made of DNA, we should be extremely careful about forcing the innocent to provide it.

Lord Justice Sedley's suggestion was that also all visitors to this country should provide DNA samples. I cannot think of any plan better suited to kill tourist and business travel to this country. Would you want to go to a foreign state that wanted to take a DNA sample off you at arrivals desk?