By Danny Shaw
Home affairs correspondent, BBC News
DNA is widely used in the UK to detect a range of crimes
The European Court of Human Rights has spoken with a strong and clear voice - retaining indefinitely the DNA and fingerprint records of unconvicted suspects is unlawful.
The 17 judges of Strasbourg's Grand Chamber were unanimous in their ruling, and they emphasised that the government must follow it - because on this issue it does not have much "margin of appreciation" or leeway.
The court said the UK was the only one of the 47 members of the Council of Europe to permit the "systematic and indefinite" retention of DNA samples and profiles from people who have been acquitted, though within the UK the arrangements apply only to suspects in England, Wales and Northern Ireland.
However, the court signalled that the government should consider following Scotland's example.
The position there, said the judges, was of "particular significance".
DNA profiles in Scotland are deleted once a person is cleared or not prosecuted. The only exceptions are for people suspected of certain sexual or violent offences.
Their DNA records can be stored for three years, and for a further two years with a judge's consent.
The court pointed out that Scotland's approach was consistent with a recommendation from the Council of Europe's Committee of Ministers, which was adopted in 1992, about the use and analysis of DNA.
The nub of what the committee said was that storage times for DNA profiles should vary according to the seriousness of the case.
So, the government has a clear direction it can travel in, to meet the court's findings, though it is likely to take some months before ministers finalise their proposals.
The question is what impact will this have on fighting crime.
In its submission to the court - and in parliamentary answers and ministerial statements - the government cites data, suggesting that by September 2005, the national database held 181,000 DNA profiles from suspects who would have been entitled to have their records deleted, under a "no conviction, no DNA" rule.
It says that 8,251 of these individuals were subsequently linked with crime-scene stains, which involved 13,079 offences including 109 murders and 116 rapes.
The court says the figures appear "impressive" - but on closer analysis it acknowledges, as the Nuffield Council on Bioethics and GeneWatch UK also have, that they are unconvincing.
The figures do not show if cases were solved entirely because DNA was retained from people who were not convicted or against whom charges were dropped. Other factors might have played a part.
The statistics also do not reveal when the DNA match was made.
The government, and police, have also given specific examples of crimes that were solved because of the power to take and store DNA.
But very few of these cases that I have seen involve the matching of a crime-scene sample with DNA from a suspect who has been through the legal process and cleared.
It is also worth remembering that the European court's ruling will not affect the police's powers to take DNA samples from people who are arrested, and to hold them for the purposes of an investigation.
However, it might well be that the ability of police in England, Wales and Northern Ireland to clear up crimes is restricted by the court's ruling, and any subsequent changes the government introduces.
Certainly, hundreds of thousands of people who are already on the database, and have no criminal convictions, will be entitled to have their records removed.
But the impact on solving crimes might not be as great as ministers and police officers fear.