Police correct not to arrest alleged drink driver

Police in Devon and Cornwall have been criticised after a driver was allowed to continue driving despite failing a roadside breath test.  Although it is normal for the press and campaigners to talk about drink drivers as if they were all murderers intent on killing everybody they see, we at London and Oxford Drink DrivingSolicitor think that the police got it right on this occasion.

In the past, roadside breath tests were crude and could only tell a police officer if somebody was under the limit or over the limit – although some also had an amber warning for those close to the limit.  Modern roadside breath test units are far more sophisticated and, if the government gets its way, may soon replace the aging police station intoximeters.

Modern roadside breath test equipment is capable of providing officers with a precise reading of the alcohol in a driver’s breath and are considered to be as accurate as the police station evidential intoximeters.  The main difference is that the roadside units lack other features of the intoximeter, such as the ability to detect mouth alcohol and there are differences in the way the machines look for the deep lung air that is key to obtaining a reliable specimen.

The driver in question is said to have provided a specimen of just over the drink driving limit of 35 microgrammes of alcohol in 100 millilitres of breath.  No precise figure has been published; however, we assume that it was below 40 microgrammes.  We assume this because in 1983 the Home Office published its Circular number 46/1983, which states that because there is a margin of error with all breath test machines, the police must not prosecute where the level of alcohol in breath is “… less than 40 micrograms (sic)”.  The reason given for this is to, “… ensure that any offender prosecuted will have a result in excess of the prescribed limit.” 

Drivers blowing below 40 microgrammes will not be charged

The Circular means that had the driver in this case blown less than 40 at the police station the police would not have been able to prosecute.

In the Devon and Cornwall case, the police officer was advised by another police officer to wait 30-minutes and then re-test the driver.  This appears to us to be an excellent use of time as a diagnostic tool.  If the driver’s blood alcohol level was rising then he would be likely to provide a higher reading after 30-minutes and could have been arrested.  If, as happened, the later test provided a lower reading then it would be obvious to the police officer that the driver could not be charged with any offence and so arresting him could not be necessary and thus any arrest would be unlawful!

As always, if you have been accused of a drink driving offence and would like advice and representation in court, whether it’s for a trial or just to help you get the lowest possible sentence, you can call the London Drink Driving Solicitor on 020 8242 4440 or in Oxford and the Thames Valley on 01869 866 490.