05. – The Drink Driving Law (Refresher)

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The Drink Driving Law


In December 2014, the Drink Driving limit in Scotland was reduced to 22µg of alcohol per 100ml breath. You may also have seen it in the media expressed in its blood alcohol limit of 50mg/100ml (0.05%BAC). This is the same limit for the Republic of Ireland.

Ireland also has a lower limit again for professional, learner, and novice drivers of 9µg/100ml.

In the rest of the UK (England, Wales, and Northern Ireland) the limit is 35µg/100ml breath for all drivers.

Today the initial roadside breath test is followed up by two additional breath tests 20 minutes apart back at the station using an evidential breathalyzer. The lowest of the two readings is used to decide whether the driver is within the legal limit or not.

It used to be that if the lowest reading is below 50µg/100ml breath (in England, Wales and N.Ireland) then a blood test could be requested.  This is no longer the case and only the breath test result is used, the reason being that the time required to secure a blood sample could give the suspect time to metabolise the alcohol and pass the blood test, subsequently getting away with drink driving.

However, there is another law which you should be aware of: The Road Traffic Act 1988:

“Section 4 of the Road Traffic Act 1988 states that a person who, when driving or attempting to drive a mechanically propelled vehicle on a road or other public place, is unfit to drive through drink or drugs is guilty of an offence.”

This means that if there is evidence of impaired driving then the police are still able to charge a driver for an offence caused by alcohol – even if the reading they give is under the legal drink-drive limit.


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