BBC News Online looks at the dashboard device that will stop drink-drivers from even starting their cars.
A driver uses an Alcolock to test whether he is safe to drive
The "alcolocks" are fitted to car ignitions and require the driver to blow into a tube.
The engine will not switch on if it detects a blood alcohol concentration above a certain threshold.
The device is being targeted at persistent drink-driving offenders, and the scheme is being tested in Bristol and in the West Midlands.
Other controls favoured
Alcohol and road safety organisations have given a cautious welcome to the trials of the devices, which work on the same principle as a breathalyser.
The researchers are approaching convicted drink drivers directly, to see if they will volunteer for the trials.
Many states in the US and Canada have introduced the alcolock, using it partly
as a substitute for the suspension of a driving licence and partly as a
preventative measure, and an alcolock trial is currently under way in Sweden.
The devices are likely to be introduced in the Road Safety Bill in the autumn.
If the bill becomes law, the first cars will be fitted with alcolocks next year.
It has been suggested that banned drivers who volunteer to fit the device could get their licences back more quickly.
The AA Motoring Trust said it was in favour of the principle of trialling alcolocks.
"The theory is fine, if you can somehow rehabilitate drink drivers into driving responsibly," said AA spokesman Richard Freeman.
"They haven't trialled them here properly yet. Problems might crop up in a trial that we haven't anticipated."
Mr Freeman said one possible concern was over the cost to the driver of using the equipment. He estimated that it would cost £90 a month for the hire of the alcolock, and £110 to install.
"That's over £1,000 a year," he said. "It's a potential barrier to people wanting to use it."
Charity Alcohol Concern said it welcomed the introduction of alcolocks - but said the best way of preventing illegal drink-driving was not to drive at all after drinking.
"You don't have to be over the drink-drive limit before you start losing coordination," said a spokesperson.
"Really to be on the safe side, it would be better if you didn't drink."
The group is also pressing for a reduction in the legal blood alcohol level, from 80 to 50 milligrams of alcohol per 100 millilitres of breath.
"We'd rather see more concentration on measures that have been shown to work in reducing the incidence of drink driving."
In 2002 - the latest year for which there are official transport department figures - there were 560 deaths in 2,800 serious injuries in drink-drive accidents.
Kevin Clinton, head of road safety at the Royal Society for the Prevention of
Accidents, said: "We think these devices will prove useful. Evidence from
overseas suggests that they are effective in reducing the likelihood of
convicted drink-drivers from re-offending while the device is fitted to their
"If the trial is successful, we would like to see these devices available as
a sentencing option.
"They may be even more effective if used in conjunction with
educational measures such as drink-drive rehabilitation schemes."