A new call to lower the drink driving limit has reopened the debate, writes motoring journalist Maria McCarthy.
Last month, the Parliamentary Advisory Council for Transport Safety (PACTS) wrote a letter to the Times newspaper calling for a cut in the drink driving limit.
It says the government should implement the recommendation from Sir Peter North in his joint report with the Transport Select Committee for the blood alcohol limit to be lowered.
The report calls for a cut from 80 milligrammes of alcohol in 100 millilitres of blood, to 50 milligrammes of alcohol in 100 millilitres of blood.
This would bring the UK in line with most other European countries and, PACTS believes, reduce fatalities and road accidents.
For and against
Most road safety groups support this move.
But Brigid Simmonds, chief executive of the British Beer and Pub Association disagrees, saying: "We are against drink driving and support random breath testing.
"However, most drink driving road accidents are caused by people significantly over the limit.
"We feel that lowering it would penalise a responsible majority who might have a small drink with a meal."
Drivers' legal limit difficulties
Drinking while also trying to stay under the limit can be a tricky business.
Different types of wine and beer have different strengths, and the effect varies depending on your weight, metabolism and whether you've eaten recently.
Keeping track at a party where you'll probably be offered a drink that's two or three times the size of a pub measure is even more difficult.
People also process alcohol at different rates, so some will recover from the effects quicker than others.
These variables are why most road safety organisations and alcohol awareness campaigns are reluctant to put a figure on the number of units a person can drink and stay under the legal limit.
TIP: Try the Confused.com alcohol units calculator to work out which drinks are likely to push you over the limit.
"We need more education in this country about the effect that alcohol has on the body," says Jeanette Miller, a senior partner at Geoffrey Miller Solicitors which specialises in defending drivers accused of motoring offences.
"The number of morning after cases we see illustrates this – people who have thought the alcohol they drank the night before has left their system when in fact it hasn't."
The consequences of drink driving can be tragic. The Institute of Alcohol Studies estimates that drink driving caused 460 fatalities in 2007.
It estimates that an additional 250 fatalities were caused by drivers and riders with raised blood alcohol levels but still under the current legal limit.
Drink driving and the law
Even if they're not involved in an accident, motorists caught over the legal limit face at least a year driving ban, as well as a fine of up to £5,000 and up to six months' imprisonment.
Causing death by careless driving under the influence of alcohol can mean a prison sentence of up to 14 years.
And if convicted for drink driving, car insurance is likely to prove expensive.
On a personal level, I made myself a promise when I passed my driving test that I would never drink and drive.
I've got a small build and feel the effect of alcohol very quickly – I'm not really safe in charge of a bar stool, let alone a car!
Also, for me drinking is about kicking back and relaxing, not worrying about whether I'll be alright with just the one.
However there is something that feels rather puritanical about sipping a mineral water or orange juice when your friends are knocking back the booze.
When I'm out on the town I want to feel I'm having a treat, so a wider, more imaginative range of soft drinks and coffees in bars would be most welcome.
The last time I was the designated driver, I was with friends in a pub which served hot chocolate.
Having one of those helped ease any feelings of deprivation while still letting me have a safe journey home.
What do you think?
Should the drink driving limit be cut? Or perhaps you think it should be against the law for motorists to drink any amount of alcohol and drive?
And what's your experience of being the designated driver - should pubs and bars do a wider range of drinks to appease non-drinking motorists?
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