Drivers who are under the influence of drugs are set to be prosecuted as part of a 'zero-tolerance crackdown' as of next year.
The new offence of driving or being in control of a vehicle with a specified controlled drug in the body is being created as a part of the Crime and Courts Bill, which is currently before Parliament.
The new law will be enforced with the use of 'drugalysers' - new devices used for measuring the amounts of various substances in drivers' systems - and will be punishable with sentences up to and including a 12-month ban, six months in jail, and a £5,000 fine.
Eight controlled substances - including cannabis, ecstasy, ketamine and cocaine - will be subject to a 'zero' limit, while higher limits will be set for controlled drugs "that have recognised and widespread medical uses", meaning those who abuse prescription medicines will also fall foul of the new law.
Road safety minister Stephen Hammond said: "Drug driving is a menace which devastates families and ruins lives. That is why we are proposing to take a zero-tolerance approach with those who drive under the influence."
Motorists' groups have welcomed the news, with Edmund King, the AA President, saying: "This is a landmark and radical step. It marks the first drug-drive limit in this country, and a zero-tolerance approach to illegal drug driving, which we support.
"We have been calling for a crackdown on drug-driving for the past five years. It is a hidden killer. But there must also be rigorous enforcement by the police."