Video cameras have an accepted and familiar role in identifying wrongdoing and in exonerating the innocent. They are now being used by police forces themselves to protect officers from being wrongly accused of misconduct - or worse.
That issue takes on an altogether more sinister tone when the officer concerned is a firearms officer, which is why a number of police forces are taking part in a pilot to identify whether chest-mounted or head-mounted cameras are more suitable for firearms officers.
One of those forces is Staffordshire, which already uses around 560 body-worn video cameras, according to the Police Oracle news website.
Assistant Chief Constable Bernie O'Reilly told the publication: "We want to make sure that we get the best footage when we deploy with different equipment and in different circumstances. Body-worn video is very effective; it captures events as they happen, often diffuses potentially violent situations and provides speedier justice for victims as offenders are more likely to plead guilty."
Following a similar trial, the Metropolitan Police is in the process of selecting a provider for 20,000 cameras to be rolled out across the force, the report said.