Our freedom of movement is being withdrawn
Ministers have previously rejected random breath-testing but it is understood that there was a change of heart when the results of the latest Christmas campaign against drink-driving were revealed.
These showed that while the number of tests carried out in England and Wales rose six per cent, the number of drivers who failed fell to 7,800 - down from 9,700 in 2006.
(The number of breath tests rose from 145,867 during the 2006 Christmas period to 155,216 last year. The number of motorists failing "fit to drive" tests - designed to detect motorists under the influence of drugs - also dropped from 666 to 550.)
So the proportion of drunk drivers dropped from 6.6% to 5% - most people would see that as a success and that the present policy is working, but somehow it is presented as a failure and that we need to do it differently. And differently in a way that causes John Spellar, a former Labour transport minister, to say .
"Yet again they are straining the tolerance of the British public, when they should be focusing on the minority who are grossly over the limit and causing mayhem," he said.
"This system has been working well for many years and has left us with one of the best safety records in Europe.
"There is a serious danger this will erode the confidence of the public in the police and create ill will."
A spokesman for the Association of British Drivers said: "It seems like an infringement of people's liberty.
"It is as if our freedom of movement is being withdrawn. We would need to be convinced that it would save lives."