A Government minister is urging car passengers to speak up to prevent drunken drivers from taking the wheel.
The comments from Transport Minister Robert Goodwill follow a survey showing a quarter of those who had been in a car with an over-the-limit driver had been too embarrassed to act.
Part of the THINK! Easter drink-drive campaign launched today, the survey showed that a number of people misjudge the effects of driving after drinking.
A third thought it was safe to drive if they waited a few hours after their last alcoholic drink, while t wo thirds said they would not be concerned about someone who drove after drinking with a meal.
Mr Goodwill said: "Everyone knows that drinking and driving is not only against the law. It's extremely dangerous. It may well be the responsibility of drivers to ensure they don't do it, but passengers can also discourage drinking and driving by speaking out.
"Clearly the majority of passengers feel confident enough to say something, but it is worrying that a significant proportion feel too shy to pipe up."
He went on: "I would urge anyone who sees someone attempting to drive after drinking to speak out confidently, take away their keys and call them a taxi.
"You could be helping them avoid a heavy fine, a driving ban or even a prison sentence. You could even be saving their life and the lives of others."
The latest THINK! campaign, which will see a series of adverts broadcast on national and regional radio for eight weeks, also urges people to plan their route home in advance after the survey found that more than 30% or people would get in a car with someone over the limit if it were an emergency or if there was no other way of getting home.