What you need to know about the drink driving limit

Carlton Boyce / 30 November 2015 ( 11 November 2016 )

Is it safe to drink and drive? What is the current alcohol drink drive limit?



Drink driving is a simple subject made complicated by folk lore, well-meant but inaccurate advice, and confusion around what the law actually says.

Our advice is never to drink and drive. Of course, we all know this but a surprising number of people still fall foul every year – and Christmas is a peak time for offending.

Here are the facts. Please share them with your friends and family.

Think you know the law? These eight new laws, introduced in the last couple of years, will affect motorists.

The current limits

The current drink drive limit in England, Wales, and Northern Ireland is 35 micrograms of alcohol per 100 milliliters of breath. The limit in Scotland is lower, at 22 micrograms of alcohol per 100 milliliters of breath.

How much is the legal limit in units?

It’s impossible to say how much the legal limit equates to in units of alcohol because the effect varies so much: in general, a tall, heavyset man will be affected less than a shorter, slimmer lady, assuming both drink the same amount.

Other factors come into play too, meaning that it is simply impossible to predict what a ‘safe’ limit is – especially when you consider that someone may pass a roadside breath test and still be adversely affected by alcohol; just one drink will affect you, slowing your reactions and impairing your judgement.

In fact, it is possible to be charged and convicted of drink driving even if you are below these limits. It is rare, but it does happen and having alcohol in your blood can also be viewed as an aggravating factor if you are involved in an accident or other incident while driving a car.

The only really safe limit is zero, so why not book a taxi, share a designated driver, or use public transport if you fancy a drink?

Have you heard about the crash for cash scam?

The police and the breathalyser

The police can breathalyse you if they have reasonable grounds to suspect that you are driving under the influence of alcohol, have committed a moving traffic offence, or have been involved in an accident. They can do so on a public road or place, or a place to which the public has ready access; a pub car park, for example, would fall under this definition.

This screening test is quick and easy and is suitable for everyone, even those with asthma or other medical conditions.

Of course, no one can force you to give a breath test but if you refuse you will be arrested and charged with refusing to give a specimen of breath. If you are found guilty, the punishment will be at least as severe as if you had given a positive test…

If you do give a positive roadside breath test you will be arrested and taken to the nearest police station where you will be asked to give another, this time on a more carefully calibrated machine.

Two tests will be taken and only the lower of the two will be used in evidence. If the result is marginal, you may be offered the chance to give a blood or urine test.

Due to the difference in the two machines, it is possible to be arrested and still give a sample that is under the legal limit, in which case you will be released without charge.  

Beware of criminals targeting motorists on motorways and slip roads

What next?

You will be bailed and will eventually appear in court to face the charge(s) against you. 

If you are found guilty you can expect a hefty fine and a driving ban, not to mention a possible prison sentence and the social stigma of now having a criminal record.

The morning after the night before

Even the fastest metabolism will struggle to process a heavy night’s drinking in time for an early morning drive the following day, leaving many at risk of inadvertently drink driving. 

The old rule – that the body can process one standard pub drink per hour – fails to take into account the dramatic variations between metabolisms.

Nor does it allow for the fact that few people serve pub measures at home, especially when it comes to spirits; a ‘normal’ home measure could well be the equivalent of a quadruple in a pub or restaurant.

The best advice is not to drive in the morning if you’ve had a lot to drink the night before. However, if you must, the only safe way to do it is to stop drinking early, drink lots of water, and test yourself with a reputable home breathalyser to check that you’re fit to drive before getting behind the wheel.

On second thoughts, just don’t do it. It really isn’t worth it.

What to do if you are a victim of road rage

Alternatives to alcohol

Having an alcohol-free evening doesn’t automatically sentence you to an evening of fruit juice or sugary fizzy drinks, either: there are lots of grown-up soft drinks on the market now that are a great alternative to alcohol. 

Who knows, you might not even miss it!

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The material is for general information only and does not constitute investment, tax, legal, medical or other form of advice. You should not rely on this information to make (or refrain from making) any decisions. Always obtain independent, professional advice for your own particular situation.