A policy of "zero-tolerance" towards motorists who take drugs and drive is being considered by the Home Office.
Drivers caught with traces of drugs in their bodies, even if their driving is unaffected by the illegal substances, would be punished, under the tough proposals by police chiefs.
The controversial plans could mean that motorists who had taken drugs several days before they were tested will be penalised because many illegal substances, such as cannabis, remain in the blood stream for weeks. A recent survey revealed that one in seven motorists admits driving under the influence of illegal drugs. A quarter of drug users said they had driven after taking cannabis and 10 per cent after cocaine or ecstasy.
The Department for Transport has also found that almost a fifth of those killed on the roads in 2004 were driving with drugs in their system, compared with 3 per cent in 1989.
Meredydd Hughes, Chief Constable of South Yorkshire and spokesman for the Association of Chief Police Officers' on roads policing, said: "My start point is to say if you take drugs you can't drive a car. If you want to take illegal drugs, catch a bus."
The Acpo proposals are being discussed by the Home Office-led drink and drug driving working group, which includes representatives from the Department for Transport, the police and the Crown Prosecution Service.
At present, it is difficult to convict motorists of drug-driving because the police need evidence not just that the driver has taken drugs but that his or her driving has been impaired as a result. Officers have to use unreliable "field impairment tests", which assess mental and physical co-ordination, to decide whether a motorist is under the influence of drugs, before blood tests.
Mr Hughes said: "I want to remove the impairment element of the existing law so it becomes an offence to drive a motor vehicle on the road while under the influence of an illegal drug. It is a substantial change. It lays down a marker, saying if you take drugs you can't drive a car. That is my start point.
"We need to look at the retention levels of the drug in the body and a scale of penalties for different drugs. The use of a motor vehicle on a road is a privilege, not an absolute right. With illegal drugs, it is almost impossible to always identify the true scale of how drugs impair driving.Reuse content