ROAD safety experts are calling for a drug-drive limit to be imposed by law after a police campaign which stopped and tested drivers found one in seven had taken illegal substances.

The RAC Foundation is demanding action to tackle the problem and says that unlike alcohol, there is no clear level at which a suspected drug driver can be charged.

Instead police have to demonstrate that the driver is unfit to drive by a complicated series of roadside ‘sobriety’ tests followed by evidence obtained by a police surgeon.

The foundation believes this is problematic as drugs like cannabis can stay in the bloodstream for up to four weeks and therefore the presence of the drug does not always prove that driver is unfit to drive.

Speaking at the London Road Safety Event last week, Edmund King, executive director of the RAC Foundation, said: ‘We realise that talking about a drug-drive limit will be a contentious issue, but it is prompted by a growing body of evidence that drugs and driving is a significant problem especially among young people and needs to be addressed.’