MORE THAN 400 motorists a month have been arrested for drug-driving since the new offence was introduced at the beginning of March, according to a nationwide survey.
But while some police forces have apprehended scores of offenders, others have arrested none.
The Metropolitan Police had the most arrests, 214, followed by Northumbria (97) Sussex (58) and South Yorkshire Police in fourth place with 55.
West Yorkshire Police had nine arrests, North Yorkshire four and Humberside 10.
The statistics were obtained by the Institute of Advanced Motorists (IAM) under a Freedom of Information Act request to all police forces in England and Wales.
The responses from the forces cover a range of dates from March 2, when the new offence of drug-driving came in, to the end of May.
Information from some forces covered only the period until the end of April, while other forces were able to give arrest details up to various dates in May. There was no response from some forces.
IAM said the figures they obtained showed there were 902 drug-driving arrests in total.
At the opposite end of the scale, details from Leicestershire, Warwickshire and Gwent showed these police forces had yet to make any arrests.
The new laws introduced in England and Wales set limits at very low levels for eight drugs commonly associated with illegal use, such as cannabis and cocaine. Eight prescription drugs were also included within the new law, including diazepam, methadone and morphine.
Police are able to use a “drugalyser” to screen for cannabis and cocaine at the roadside. Even if a driver passes the roadside check, officers will still be able to test at a police station for ecstasy, LSD, ketamine and heroin, as well as other drugs.
IAM highlighted the 2010 North Report, by Sir Peter North, which looked at the prevalence of illicit drug use among drivers in Britain and said drugs could be a factor in as many as 200 deaths every year.
IAM chief executive Sarah Sillars said it was a concern that there was such a variation.
She said: “I am sure the majority of law-abiding drivers would like to know why there is such a variation in the data we have received from police forces.
“It would be unfortunate if some people got the idea that some areas are softer on drug-driving than others.
“It is very clear from our survey that the new drug-driving law has just scratched the surface of a much bigger issue.
“It would seem Sir Peter North has been proved correct when he said there is a significant drug-driving problem which is out of all proportion to the number of accidents reported to the police. We are delighted that the legislation has been introduced and people are being caught.”
The IAM said: “Essex Police stated they were unable to extract specific drug-drive data from their drink/drugs-drive data, and they were not obliged to extract drug-drive data under the Freedom of Information Act.”