Better equipment is needed to tackle the growing problem of drug driving, the RAC has warned.
The motoring group said a testing kit similar to the road side breath test for alcohol was needed to assess the 1 size of the problem of drug driving in the UK.
It comes after pop star George Michael was jailed for eight weeks for drug driving when he admitted crashing his car while under the influence of cannabis at London's Highbury Corner Magistrates' Court.
Professor Stephen Glaister, director of the RAC Foundation, said: "The dangers of drink driving have long been known, but this case highlights the big risks of driving under the influence of drugs - be they illegal or prescription.
"Drug driving is believed to be widespread but the 1 scale of the problem is hard to quantify because of the lack of testing kit similar to the roadside breathalyser used to detect alcohol.
"But the Government has recently announcement that new equipment for use in police stations is soon to be trialled and could be rolled out to all police forces within two years."
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