Video footage needs the same care as other evidence, an FBI expert has warned.

The increasing use of CCTV footage, phone clips and body worn video as evidence poses risks for officers, an international conference has heard.

A meeting of the International Council of Police Representative Associations (ICPRA) was told by a leading expert that officers cannot afford to presume that video evidence can be taken at face value.

And Federation leaders have now warned they will be challenging forces over training, guidance and specific cases including conduct investigations.

The conference in Scotland heard from Grant Fredricks, a US Justice Department consultant and contract instructor for the FBI National Academy.

His presentation, described as “jaw-dropping” and “incredible” warned video evidence if used incorrectly, could potentially lead a jury or standards investigation in the wrong direction.

An expert witness would be able to spot problems such as the film speed of a clip, editing sequences and camera angles.

But an officer won't be aware of the technical limitations.

Footage that shows someone lunging at an alleged victim could have been sped up by the algorithm supporting the camera. And that would make a difference to the balance of evidence in an assault case.

Metropolitan Police Federation Chair Ken Marsh told Police Oracle: “The presentation was incredible. An expert can detect something quite different to an officer. What was made very clear is that we should always challenge what is put in front of us. We need to action further, now.”

He added: “We’ve got to understand properly the usage of body worn video. For far too long, we’ve just accepted what management have accepted on storage. The more they store, the less they have the ability to show what has been done correctly.”

Training needs to be formalised for officers in every force another Fed leader warned, highlighting that sports referees have more training than an average police officer.

David Hamilton said: “It’s about interpretation of the footage. Some US forces are providing at least a two day course. We give investigators nothing. It needs to be done within a proper structure. Defence lawyers are catching on.”

Evidence gathering is one area of potential failure. Retrieving clips from CCTV systems takes up a significant amount of officer time. Officers were advised not to be tempted to use their BWV to screen shot footage in a bid to save time. It is a high-risk practice that could impact on an investigation.

Mr Marsh said: “Body worn video is a fantastic piece of kit but it has to be treated with care.”

The Police Federation has also raised concerns about the use of video evidence – particularly when it is used in prosecutions against officers or misconduct hearings.

Its annual conference last month heard how a traffic officer was aquitted at Kingston Crown Court after being prosecuted over a pursuit involving a moped rider who died after hitting a lamp post.

Sections of video evidence showed a continuous pursuit. But expert witness Roger Gardner, Driver Training Manager with Lancashire Constabulary, revealed that among the footage was a crucial 17 second segment which had no police involvement but showed the rider repeatedly mounting the pavement at speed.

Ken Marsh said it was “absurd” the case had ever made it to court and conduct reps will now challenge video evidence against officers more strongly.

Official guidance is available on best practice from the College of Policing – and the Fed leaders warned officers need to see it.

The College guidance is: “CCTV makes a significant and often critical contribution to the detection of many crimes. The extent to which it can be secured and relied on in court depends upon the evidence being gathered in a forensically sound manner by a competent individual.”

David Hamilton said officers should exercise caution: “This has absolutely rattled my confidence in how we use video footage both internally and externally. They say the camera never lies. It does. ”