DRIVERS who snooze in their car after a night on the booze risk a ban, a lawyer has warned.

Even though the engine has been switched off, motorists risk 10 points on their licence if police can prove they intended to drive while still over the limit.

Nick Ross, a criminal lawyer and motoring offence specialist with Russell and Russell solicitors in Bolton, said: “Drivers also put themselves at risk of a driving ban if they already have three points for a single speeding offence.

“This is because an additional 10 points will tot up to more than 12 points, leading to the loss of their licence.”

When drivers tot up 12 points or more on their licence, they are required to go to court and will normally receive a minimum six-month driving ban.

As a rough guide, road safety charity Brake says sobering up takes an hour per alcohol unit, starting an hour after the last drink.

Mr Ross said: “In my view, nine out of 10 police officers who find someone slumped drunk inside their car, behind the wheel, will conclude that they intended to drive whilst still over the limit and this puts the driver in danger of prosecution.

“It’s tempting for motorists who have drunk too much to fall asleep in the car, thinking they can sleep off the effects of alcohol.

“But police officers, particularly during the festive season, are unlikely to overlook a drink driver they find asleep in a car.

“This has to be another reason for motorists who want to have a drink over Christmas to leave their car at home. Otherwise they could face prosecution and find themselves off the road.”

During 2011’s month-long Christmas enforcement campaign, English and Welsh police forces stopped and tested 157,000 drivers, making 7,200 arrests According to road safety charity Brake, to help avoid “morning after” drink driving, as a guide, you can work out the time it takes to sober up by counting units consumed, and, starting from one hour after finishing drinking, adding an hour for each unit.

This means that if you drink four pints of 4.5 per cent lager, at 2.6 units each, and finish drinking at 11pm, you should avoid driving until at least 10.15am the next morning.

A police spokesman said sleeping in a car is not an offence, but it is a crime for a person to drive, attempt to drive or be in charge of a vehicle after consuming above the prescribed legal drink driving limits.

People sleeping in their car with the intention of driving home in a couple of hours, with their engine on or with the keys in their pocket, run the risk of being in charge of a vehicle while over the limit.

The spokesman said an offence would not be committed if someone slept in their car after drinking and gave their keys to a landlord when the pub was closing until the following afternoon, for example.