POLICE Scotland has been criticised after it emerged the force does not record the number of roadside breath tests carried out outside of drink-drive campaigns.
The Lib Dems said greater transparency was needed over breath tests as a way of evaluating the use of police time.
The party’s justice spokeswoman, Alison McInnes, had asked the Scottish Government for figures showing the number of times that motorists were breathalysed and the number of positive results.
But Justice Secretary Michael Matheson said the figures were not recorded outside of drink-drive campaigns, such as those carried out over the festive period.
McInnes said it was “odd” that police did not collect the data.
“Breath tests have been key to preventing and detecting the menace of drink-driving on our roads, but without this information it is nearly impossible to evaluate the extent to which it is an effective use of police time,” she said.
“We saw that with stop and search. Hundreds of thousands of people were being subjected to so-called consensual stop and searches with very little being found.
“If we are to ensure we have the right balance between protecting the civil liberties and the safety of motorists, we need an evidence-based approach to policing. I hope that Police Scotland will reconsider this and adopt a position of greater transparency on roadside breath testing.”
The number of drivers being caught over the limit has fallen steadily over the past decade and is likely to fall even further following the introduction of the new legal limit last year.
In 2006-7, a total of 11,704 motorists were found to be driving under the influence, compared with a total of 6,079 in 2013-14.
In December, a change in the law reduced the legal alcohol limit from 80mg to 50mg in every 100ml of blood.
In the three weeks after it came into force, 255 people were found to be driving under the influence of drink or drugs, compared with 348 a year earlier – a fall of 27 per cent.
Drivers are required to give a breath test following a collision or a moving traffic offence. Police officers can also breathalyse a driver when they have reasonable cause to believe there is alcohol in their system.
Chief Superintendent Iain Murray said: “There are also a range of other statutory powers that enable an officer to stop vehicles or to direct their movement for a number of reasons including the production of documents or to examine the vehicle for defects.
“In addition, all road policing officers in Scotland are trained to carry our preliminary impairment tests in circumstances where they have reasonable cause to believe that a motorist’s ability to drive is impaired through the use of something other than alcohol.
“There are therefore many more vehicle stops each year than there are breath tests carried out, as it is at the discretion of the individual officer to determine whether there are legal grounds to administer a test in each set of circumstances.”
He added: “I am confident that the increase in the number of drivers being stopped and spoken to by road policing officers, and the reduction in the number of offences being detected, shows that fewer people are now choosing to put themselves and others so needlessly at risk by drinking and driving.
“I also believe that this change in attitude and behaviour is now well established in Scottish society as a result of the limit change.”