Guidelines maintained by the Association of Chief Police Officers (ACPO) say that DNA taken from suspects should only be deleted in exceptional cases. A panel of judges at the Supreme Court ruled that excessive retention of DNA profiles violated a person's right to privacy under European human rights law.
"The majority grant a declaration that the present ACPO guidelines are unlawful because they are incompatible with ... the European Convention on Human Rights (the Convention)," a press summary (2-page / 111KB PDF) of the Supreme Court ruling said.
The Court said that it was not necessary for it to force a change in UK law because the Government was planning to bring new laws covering the retention of biometric data into force later this year.
"It is, however, open to ACPO to reconsider and amend the guidelines in the interim," the summary of the Court ruling said.
Two of the seven judges disagreed with the ruling, the summary said.
"[Lords Rodger and Brown] would have dismissed the appeals. In their view, the history shows that Parliament's purpose in [creating a new law to destroy data with discretion] was to ensure that in future samples taken from suspects would be retained indefinitely: Therefore, the police had no choice but to retain the data," the summary of the ruling said.
In 2008 the European Court of Human Rights ruled that indefinite retention of DNA data was unlawful under the Convention. The ruling overturned a House of Lords decision that automatic retention by police forces in England and Wales of DNA samples did not interfere with a person's right to privacy.
That case involved an anonymous man known as S and Michael Marper in 2004. The House of Lords said that the retention of their data did not violate the European Convention on Human Rights, which became UK law in the Human Rights Act.
Although the European Court of Human Rights' rulings are not binding the Supreme Court said that the Human Rights Act required it to interpret laws "in a way which is compatible with the [European human rights] Convention," the press summary of the ruling said.
The ACPO guidelines were introduced to supplement the Police and Criminal Evidence Act (PACE). The court said that the purpose of the guidelines had been misinterpreted.
"It is uncontroversial that the statutory purpose of [PACE] was to remove the requirement to destroy data after it had served its immediate purpose so as to create a greatly extended database," the summary of the ruling said. "The extended [DNA] database was to facilitate the prevention of crime, the investigation of offences and the conduct of prosecutions."
"However, this does not mean that Parliament intended that, save in exceptional circumstances, the data should be retained indefinitely. Rather, Parliament conferred a discretion on the police to retain data," the summary said.
The judges made their ruling in a case involving two men who were appealing against decisions not to delete DNA information stored about them.
One of the men, GC, had a DNA sample, fingerprints and photographs taken after he was arrested on suspicion of assaulting his girlfriend, the summary of the ruling said. The charges were subsequently dropped. The other man, C, was acquitted of rape in 2009 and had requested that his finger prints and DNA be deleted from police records, the summary said.
"Their requests were refused as there were no exceptional circumstances within the meaning of the ACPO guidelines," the summary of the Supreme Court ruling said.
The Supreme Court ruling contradicts what Northern Ireland's High Court of Justice ruled in January. That Court ruled that police retention of a 14 year old boy's DNA was not unlawful. It said that it had to ignore the non-binding European ruling on S and Michael Marper and follow what the "precedent" the House of Lords had established in that case.
The Government had planned to allow the retention of police-gathered DNA data for 12 years but in 2009 said that it would change that in many cases to six years. A change to the law is expected to be put in place by the Government later this year.