What are the Drink Driving Limits?

It’s that time of year where we all look forward to our work Christmas party. A night where we can celebrate the achievements of the year and enjoy a usually complimentary night of food and drink. Most of us make alternative arrangements for travelling home but it can be difficult if you don’t live that close to the venue. It’s dark, cold and wet and taxis are busy and expensive so there’s always a few in the office who say they will drive. But how much can you really drink and still be ok to drive? It is not an easy question to respond to as there are no definitive guidelines however, Ruth Peters, Specialist Motoring Solicitor, considers the issue in greater detail.

Drink Drive Offence – The Limits

In England and Wales, the drink drive alcohol limits are as follows:

  • 80mg of alcohol per 100 millilitres of blood
  • 107 milligrams of alcohol per 100 millilitres of urine
  • 35 micrograms per 100 millilitres of breath.

In Scotland the limits have been reduced and they all correlate to a much lower limit of 50 micrograms of alcohol per 100 millilitres of blood.

In general the police will usually administer a breath test and therefore it is the breath alcohol level that most drivers are familiar with. However there are specific circumstances where the Police will go on to make a requirement for a blood or urine specimen.

Drink Driving – Units of Alcohol

Alcohol is usually measured in ‘units’ of 10 millilitres of alcohol. This is the amount of alcohol contained in a half pint of beer of 3.5 percent ABV or a single 25ml pub measure of spirits.( source: https://en.wikipedia.org/wiki/Alcohol_by_volume)

However, alcoholic drinks in recent years have become much stronger. It used to be far more typical for lager to be much weaker; however it is now uncommon to find lager being served in pubs that is less than 4% ABV and in fact most are stronger.

Many would probably be surprised to note that one pint of 5% lager would in fact contain 2.8 units of alcohol and indeed a 330ml bottle of 5% ABV lager would in fact contain 1.7 units. It has become far more fashionable for individuals to drink bottled lager in certain bars and many feel that because they contain a small volume, that they can drink more often and yet still be ok to drive.

Wine is one drink that frequently causes problems for all motorists. Wine is generally served in either small glasses, standard size glasses or large glasses. A standard glass is generally defined as 175ml with a large glass being 250ml. It is becoming more and more unusual for small glasses to be served, however these tend to contain 125ml. Again, wine comes in different strengths and white wine is generally anywhere between 12% and 14%. A standard size glass of 14% ABV white wine would in fact contain 2.45 units, with a large glass being well over 3 units. Unsurprisingly, it is therefore very unlikely for an individual to drink two large glasses of wine and be under the drink drive limit.

(source: https://en.wikipedia.org/wiki/Unit_of_alcohol)


So how is alcohol metabolised?

The rate of absorption of alcohol into the bloodstream is unpredictable. There are a number of factors such as the level of hydration in the body, the type of alcohol consumed and whether food has been eaten at the same time. As a broad rule of thumb, alcohol in the drink is generally absorbed after an hour of when the drink has been finished.

Alcohol is processed through the liver and then excreted through urine. The rate at which alcohol is metabolised and removed from the blood is very unpredictable and will depend on an individuals weight, sex, and whether they have had any food during the day. It is simply not possible to predict how your body will metabolise alcohol on a given day as the factors involved are simply too variable.

Furthermore, the capacity of your body to metabolise alcohol is finite. This is probably limited to 16-20 units per day. If you are a heavy drinker and drink most days at about this level, you will probably never be below the drink drive limit. You might also want to consider whether you wish to seek assistance in respect of your drinking.


The morning after the night before

The Christmas party night is usually a particularly heavy night out and it is extremely likely you could still be over the limit in the morning. The body may simply not have had opportunity to metabolise the alcohol throughout the night. In addition if you are feeling a little ‘delicate’ as a result of your night out then we would suggest that irrespective of your alcohol level its probably best to simply not drive.


Being unfit to drive through drink

Even if the alcohol you have consumed would put you below the drink drive limit, it does not necessarily mean that it would not effect your driving. We all know the feeling after one glass of wine when you feel a little tipsy, especially for those of us who are not regular drinkers. Alcohol can still effect your driving and if you have an accident following a drink, whilst you may still be under the limit, this would certainly be an aggravating factor.

In conclusion, the only way to be safe if you are not over the drink driving limit is to not drink any alcohol if you are driving. Make alternative arrangements for traveling home. Perhaps share a taxi with your friends or see if a family member id able to collect you. Make sure everyone is safe and remember #nonefortheroad

Specialist Motoring Solicitor

Written by Ruth Peters, at Olliers MotorLaw. If you are facing prosecution as a result of drink driving please contact out Specialist Motoring Lawyers on 0808 168 0017.

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