In its report, The Forensic Use of DNA and Fingerprints: Ethical Issues, the council recommends that police should only be allowed to permanently store bioinformation from people who are convicted of a crime.
Today, the police of England and Wales have wider sampling powers than the police force of any other country, and the UK has (proportionally, per head of population) the largest forensic database in the world.
When the police first began using DNA, consent was required before samples could be taken. A succession of Acts of Parliament and legislative amendments has increased police powers of sampling; the police can now take DNA samples from all persons arrested, without their consent, for recordable offences (an "arbitrary" classification), and retain the samples indefinitely regardless of whether the person arrested is subsequently convicted or even charged.
In response to comments from the Home Office that retaining the DNA of people who were innocent at the time of arrest had helped to solve crimes they committed years later, the Nuffield Council stuck to its guns. "There has to be a limit to police powers," said Dr Carole McCartney, one of the report's authors. "DNA shouldn't be retained simply on the basis that it might turn out to be useful."
She added that many of the statistics from the Home Office were "inconsistent, incomplete and confusing" and that much of its evidence consisted of anecdotal accounts of "horrible men caught with DNA"."Link to Original Source