Drivers will be allowed to get behind the wheel if they have traces of illegal drugs such as cocaine or cannabis in their system under new drug driving limits being set by the government for the first time.
But motorists who exceed certain thresholds of eight prescription and eight illegal drugs including cannabis and cocaine will be prosecuted for being “over the limit” in the same way as drink-drivers.
Ministers also accepted they would have to re-examine a proposed limit for amphetamine to avoid the risk of prescribed medicine users being unfairly penalised.
The limits for each individual drug reflect the speed at which they are broken down by the body, and are designed to prevent people being prosecuted for taking medically approved quantities of prescribed drugs or having tiny traces of illegal substances in their body.
The government decided to set permissible amounts, rather than a “zero” limit, because certain prescribed medications can leave trace effects in the body.
A limit of zero for illegal drugs would have risked people being penalised for accidental exposure such as inhaling cannabis smoke in a public place, or for having traces of substances in their system long after all effects have worn off.
The new limits, set by the government following a consultation on advice of doctors, include 10 micrograms of cocaine, two micrograms of cannabis and one microgram of LSD per litre of blood.
For prescription drugs, limits include 80 micrograms of morphine, 500 micrograms of methadone and 550 micrograms of diazepam per litre.
In comparison, the legal limit for alcohol is 80 milligrams of alcohol per 100ml of blood – the equivalent of 800,000 micrograms per litre.
The laws are part of the first legislation making driving with specified limits of drugs in the body an offence.
Ministers said they would have to revisit a proposed limit on amphetamine of 50 micrograms per litre of blood, because there had been “significant concerns” raised during consultation.
Doctors feared patients taking medically approved levels of attention deficit hyperactivity disorder medication could have crossed the proposed threshold.
Robert Goodwill, the road safety minister, said the limits sent “the strongest possible message that you cannot take illegal drugs and drive”.
“This new offence will make our roads safer for everyone by making it easier for the police to tackle those who drive after taking illegal drugs,” he said. “It will also clarify the limits for those who take medication.”
David Bizley, technical director of the RAC, said the limits were “clearly good news for law-abiding motorists”.
Edmund King, president of the AA, added: “Official figures show there are around 200 drug-related deaths on our roads each year but we believe that the figure is much higher as victims aren’t always routinely checked for drugs after crashes … it is heartening that progress is being made towards taking drug-driving off our streets.”
By Nick Collins
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