The benefits of body worn cameras being used by police in Northamptonshire cannot be proven, a civil liberties group says, after revealing the county has spent more than almost every other force on them.
A report published by Big Brother Watch has revealed that UK police forces have spent £22.7 million equipping officers with 47,922 body worn cameras - but are unable to show how many guilty pleas or convictions have been obtained based on footage from the technology.
Northamptonshire Police has spent £6.8 million - the fourth highest amount in the country - introducing the technology.
It has also bought the tenth highest numbers of the devices across the country, 1,271.
The small cameras attached to the uniform of patrolling officers have been billed by both the police and the Crown Prosecution Service (CPS) as critical for reducing violence and improving transparency, Big Brother watch says.
Chief executive of the group Renate Samson, said: “The police repeatedly reassure the public that body worn cameras will enhance transparency, create better relations, and improve prosecution rates, but despite 71 per cent of forces rolling out nearly 48,000 cameras, these benefits are yet to be conclusively proven.
“It says little for the approach to transparency that neither the police nor the Crown Prosecution Service could tell us how often footage from the cameras has been used in court proceedings.
“Police trials of the technology have proven inconclusive and problems have been reported with the cameras themselves.
“If the future of policing is to arm all officers with wearable surveillance, the value of the technology must be proven and not just assumed. It is not enough to tell the public they are essential policing tools if the benefits cannot be shown.”
In 2010 police across the UK had only spent £2.2million on 2,843 cameras. The Metropolitan Police has spent more than any other force since then at £15.5 million.
"With such an increase in investment, it would be logical to assume that the police had determined conclusively that the technology was indispensable," the Big Brother Watch report states.
Northamptonshire Police has been approached for comment.