The Drink Drive Limit Myth


Drink driving is considered to be a serious misdemeanour in the eyes of the law – and with good reason. The negative impact of alcohol upon spatial awareness, reaction times and general judgment can wreak potentially devastating consequences on the lives of the inebriated motorist and any number of other innocent individuals. In order to crack down on drink driving, almost all nations now impose limits upon the amount of alcohol that it is legal to have within one’s system when in charge of a vehicle.

Despite the best intentions of the authorities, there pervades a myth about drink driving which undermines all of their best efforts to thwart it. It is fair to say that the propagation of this myth is in fact somewhat attributable to the authorities themselves: through their insistence upon pushing the idea of ‘units’ of alcohol to the public. A unit of alcohol is the equivalent of 10ml of pure alcohol, and the unit system exists for the most part to demonstrate the quantity of alcohol within a particular drink; its main purpose is to act as a benchmark for health purposes. Contrary to popular public opinion: the number of units of alcohol consumed does not necessarily have a bearing upon a motorist’s adherence to the drink drive limit…furthermore, in the UK there is not a drink drive limit as such, but a series of drink drive limits.

These three limits are intended to represent parity and at the time of writing are (in the UK):

-35 microgrammes of alcohol in 100 millilitres of breath.
-80 milligrammes of alcohol in 100 millilitres of blood.
-107 milligrammes of alcohol in 100 millilitres of urine.

It is worrying that a huge number of drivers are not in fact aware of these figures and instead abide by their own set of parameters (usually based on an assumption about units). Given the vast number of variables which impact upon the levels of alcohol as measured in breath, blood and urine it is nigh on impossible to accurately calculate your fitness to drive following on from even one alcoholic drink. Possible factors which can affect alcohol levels include (but are not limited to): height, weight, gender, metabolism and how much food has been consumed recently. Given the vast margin for error there is only one way to be certain that you’re legally safe to drive: don’t drink anything prior to taking control of a motor vehicle. Just because many motorists subscribe to a myth about the drink drive limit does not mean that the police or prosecutors do and nor does it make driving under the influence of alcohol anywhere near safe.