Devon and Cornwall Police could be forced to reveal the locations of its secret car-tracking cameras after a landmark information rights ruling.
Senior officers warned that exposing its covert network of automatic number plate recognition (ANPR) cameras would put the public "at risk" and damage investigations into organised crime. It is also feared that the ruling could lead to other forces being ordered to release the information, creating a national map of cameras which could undermine counter-terrorism operations.
"ANPR has been a fantastic weapon in our fight against crime," one senior Devon and Cornwall Police officer told the Western Morning News.
"It has been a huge success, particularly in taking millions of pounds worth of drugs off the streets. If we are forced to reveal their locations, then other forces will have to follow, and that raises serious issues particularly around counter terrorism.
"Giving away that level of detail is frankly ridiculous. It will put the public at risk."
The locations of the static cameras – which "read" number plates and rapidly compare them against "hotlist" databases – has always been a jealously-guarded secret. Devon and Cornwall Police has admitted it operates 69 cameras, split between fixed sites and vehicles, which "read" almost 79 million plates last year.
The network has delivered some spectacular successes, most notably in the fight against illegal drugs.
Only last month, police successfully dismantled a major drugs gang which supplied more than a million pounds worth of cocaine to the Westcountry. The smuggling ring – including Stephen Procter, 38, of Ashford Road, Plymouth, and 41-year-old Shaun Battle, 41, of The Down in Bere Alston, Devon – only unravelled after one of the gang was "pinged" by an ANPR camera for failing to insure his car.
Courier Christopher Leader was stopped by officers on the M5 in Devon in August 2009. Inside the car, police found five kilos of cocaine worth £250,000.
The cameras, though, have proved highly controversial, with MPs complaining that the roadside network had been expanded "by stealth".
Civil liberties groups have also warned they could be used "as a tool of mass surveillance" with records – even for innocent motorists – being kept on a police database for a minimum of two years. It means motorists who routinely pass ANPR cameras, which are known to monitor main routes such as the A30, A38 and M5, will be on the police database for life.
The locations of the cameras were requested under the Freedom of Information Act by Steven Mathieson, news editor at Guardian Government Computing, in July 2009.
The force refused on the grounds that it revealed where they were stationed would "be likely to prejudice the prevention of crime". It also blocked the move after an internal review, a decision which was supported by the Information Commissioner.
Mr Mathieson then appealed to the Information Rights Tribunal which last month found in his favour, ordering that the information be disclosed within 35 days. Its ruling said: "The tribunal considers that there was, overall, a weak case made by the additional party (Devon and Cornwall Police) as to why it thought that disclosure of the information sought would be likely to prejudice policing."
It added: "The tribunal considers that in all the circumstances, the public interest falls on the side of disclosure in this case, so as to allow for debate about the strategic use of the cameras and the reasons for their deployment."
The decision is known to have raised major concerns within the Association of Chief Police Officers and particularly for the Police Service of Northern Ireland.
Devon and Cornwall Police have now confirmed they are seeking leave to challenge the ruling in the Court of Appeal while the battle could ultimately be decided in the Supreme Court.
A spokesman said: "The force believes that revealing the exact location of ANPR sites will seriously reduce their impact as a crime fighting tool in identifying suspects and offenders. There is no doubt that since the advent of ANPR the police's ability to proactively target criminals on the road network has increased dramatically.
"Showing a criminal the exact location of a camera will make those cameras easier to avoid and thus make capturing criminals more difficult. While the force accepts the need for transparency and the public's right to information whenever possible, revealing the location of covert policing resources goes far and beyond this."