Legislation to make drug-driving a specific offence was welcomed by road safety groups today.
The legislation, announced in the Queen's Speech, was "an incredibly important step forwards", said charity Brake.
Confused.com said drug-driving was a "hidden danger which is going unnoticed".
Until now police have had to demonstrate that driving had been impaired by drugs to prosecute.
Under the proposed legislation it will automatically be an offence to drive a motor vehicle if you have certain controlled drugs in your body in excess of specified limits. This will make it much easier for police to take action against drug-drivers.
Devices to screen for drugs in the body are expected to receive type approval from the Home Office by the end of the year.
Road safety minister Mike Penning said: "Drug-drivers are a deadly menace - they must be stopped and that is exactly what I intend to do.
"The new offence sends out a clear message that if you drive while under the influence of drugs you will not get away with it."