Drink driving

Alcohol seriously impairs a driver's judgement, coordination and reactions. It can make you a hazard to yourself, your passengers, other road users and pedestrians. This is why drink driving is such a serious offence.

The limits

Alcohol in the body can be measured in the breath, blood or urine. A driver will be found guilty of drink-driving if he or she has more than:

• 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.

As a rough guide, this equates to no more than four units of alcohol for men, or three units for women. But studies show driving skills are affected after just one unit, which means you are at greater risk of having an accident even if you are below the legal limit.

If the lower of the two breath readings the driver has given is 39 microgrammes or below, they should be released either without charge or with a caution.

If the reading is between 40 and 50 microgrammes then they must be offered the option of providing an alternative specimen of either blood or urine.

On average, 3,000 people are killed or seriously injured each year as a result of drink-driving.

If the lowest sample given is over 51 microgrammes per 100 milliliters of breath, the driver will be charged and sent to court. There will be a heavy fine and they will lose their driving license for at least 12 months.

Different drinks contain different alcohol content by volume. Its affect also depends on factors such as body size, gender, metabolism and how used you are to alcohol, all of which can make drinking guidelines confusing.

In short, one pint might have a stronger affect on you than on the big geezer propping up the bar. So if you're unsure how much you've had, don't drive. Ideally, if you've enjoyed a drink, don't get behind the wheel at all. As for sobering up, give yourself at least an hour for every half pint you've had - but even then the smart move is to stay out of the driving seat.

The penalties

Drivers found to exceed the limits detailed above are automatically given a minimum one-year disqualification. You could also find yourself paying a fine of up to £5,000 and/or up to six months imprisonment.

A subsequent offence within 10 years will result in a minimum disqualification of three years and the possibility of the driving licence being revoked.

Failing to give a roadside breath test could result in a fine of £1,000 and four penalty points on your licence.

If you refuse to provide samples for police analysis after driving, or attempting to drive while under the influence of alcohol, you could be fined up to £5,000 and/or six months in prison. There is also a mandatory disqualification for at least 12 months for a first offence, or at least three years for a second offence within 10 years.

The tests

In order to check whether a driver has more than the permitted amount of alcohol in his/her body, the police will carry out a roadside breath test:

The police can breathalyse anyone who they suspect is driving after excess alcohol, who is committing a moving traffic offence, or has been involved in a road accident, however minor, even if there is no suspicion of alcohol

If the test is positive, the driver will be arrested and taken to a police station for a further breath test, or in some circumstances a blood or urine test

A driver who fails to blow into the device properly or refuses to take a test, will still end up with a heavy fine and his or her licence endorsed with three or four penalty points.

No more blood tests

Until March 2011, if a roadside breathalyser test detected an amount of alcohol less than 40% over the legal limit (between 35 and 50 micrograms of alcohol per 100 millilitres of breath) accused drivers had the right to demand a blood test at a police station. Blood tests were often not taken until several hours after arrest, so some drivers used them as stalling tactic to give themselves time to sober up. This right has now been revoked.

The statistics

• Every week in the UK, 10 people will die as a result of drink-driving
• Young men in their 20s are four times more likely to be involved in drink-drive accidents than other age groups
• On average, 3,000 people are killed or seriously injured each year as a result of drink-driving
• In 2008, the number of people estimated to have been killed in drink drive accidents made up 17% of all road fatalities
• Men aged 20-24 are the most likely group to fail a breath test when they have been in an accident. Five per cent were over the limit compared to an average of 2.7% for all ages.

How to avoid drinking and driving

Don't leave yourself open to temptation when you've had a drink - if you've travelled by car, leave your keys with someone else or use public transport or a taxi

Keep tabs on yourself - one pint can give you false confidence that you can manage another one and still be fit to drive. Rather than risk it, simply don't drink at all if you'll be in the driver's seat afterwards

Remember that alcohol stays in your body for up to 48 hours. If you will need to drive the morning after, figure this into your evening plans - stop drinking early and stick to drinks with low alcohol content.

Updated: 24/03/2011