The rules state information must be relevant, up to date and not excessive
Five police forces which challenged a ruling that they should delete records on criminal convictions from their database have won their appeal.
The court of appeal said convictions, however old and however minor, can be of value in the fight against crime.
The court said that as a result the retention of that information should not be denied to the police.
The forces said if they had lost, they may have been forced to delete details of as many as one million people.
The police added if the original ruling had been upheld, the result would have been a "liars' charter" - where people would be able to deny criminal convictions on job applications if they knew the deletion deadline had passed.
'However old or minor'
Three judges ruled that retaining information was far easier to justify than actually disclosing the information to others.
"If the police say rationally and reasonably that convictions, however old or minor, have a value in the work that they do, that should, in effect, be the end of the matter," said Lord Justice Waller, sitting with Lord Justices Carnwath and Hughes.
The appeal was made by the chief constables of the Humberside, Staffordshire, Northumbria, West Midlands and Greater Manchester forces.
The five convicted people who had contested the case were refused permission to appeal to the Supreme Court.
The Association of Chief Police Officers (Acpo) welcomed the ruling, adding that "the ramifications of losing the appeal were potentially huge".
Ian Readhead, Acpo director of information, told the BBC: "This data assists police officers in their work in preventing crime and protecting the public and the loss of such valuable information would have been detrimental to that.
"Although principally used for police purposes, these records are also critical to the courts, the Criminal Records Bureau, the Independent Safeguarding Agency, the Crown Prosecution Service and the Home Office, who all supported this appeal."
But Anna Fairclough, a lawyer for the civil rights group Liberty, said the judgement "forgets the privacy rights of millions of people".
She said: "Exceptions to the Rehabilitation of Offenders Act and the net of employment vetting are being cast so wide that people will be forever haunted by the minor indiscretions of their youth.
"We need a tighter rein on the circumstances when spent convictions can be disclosed."
Held for 100 years
The original ruling came about after five people complained to the information commissioner because their criminal records showed up when they applied for jobs.
One of the cases was a record held by Humberside Police about the theft of a 99p packet of meat in 1984. The person involved, who was under 18 at the time, was fined £15.
Another, held by West Midlands Police, referred to a theft which took place more than 25 years ago, for which the individual was fined £25.
And a third, held by Staffordshire Police, related to someone under 14 who was cautioned for a minor assault.
Under current policy, criminal records remain on the police national computer for up to 100 years.