Retrospective facial recognition is most often used to compare images from an investigation, such as CCTV footage, with pictures held on the Police National Database.
The report said: “We found that forces didn’t use retrospective facial recognition (RFR) consistently.
“Legislation hasn’t kept up with developments in facial recognition technology, which is contributing to uncertainty and a fragmented approach.
There is no comprehensive statutory framework governing the police use of facial recognition technology.
“We found that some images which should have been deleted under existing retention rules remained available for facial recognition searches.