People who take drugs before getting behind the wheel of a car believe it is a much more acceptable thing to do than driving while drunk, according to a Government study.
Drug drivers believe their abilities behind the wheel are not seriously impaired by taking substances such as cannabis, cocaine and MDMA and that in any case they are unlikely to be stopped by police, the research found.
The scale of drug driving is difficult to calculate as statistics are not always recorded, but research suggests that levels are similar to drink driving.
The law on drug driving in England and Wales was tightened last month, giving police powers to test for cannabis and cocaine through a saliva swab at the side of the road. Those found guilty face up to six months in jail, a £5000 fine and an automatic year-long driving ban.