Drivers will be stopped by police and tested for drugs by the side of the road in a war on drug-driving this Christmas and New Year holiday.
The Home Office has approved roadside testing kits that will analyse samples of saliva instantly to detect illegal substances as well as so-called "legal highs".
Police will also use the kits to catch drivers who have taken prescription medicines, including strong painkillers, sleeping pills and drugs to treat anxiety, that can impair their ability to concentrate on the road.
Ministers are to order police to carry the "drugalyser" kits alongside conventional "breathalysers", which test motorists for alcohol consumption. Officers are expected to begin using the equipment within days.
The focus on drug-driving comes after decades of campaigning against people who drink and drive.
Police chiefs and ministers believe a growing number of younger people are taking illegal drugs such as cocaine, ketamine and cannabis before driving because they think they will not be caught.
The saliva tests, which have been approved for roadside use for the first time, will speed up the process of identifying offenders before substances leave their bloodstream.
At present, officers have to arrest suspects and take them to a police station to undergo time-consuming blood tests that must be conducted under medical supervision.
The wait for a doctor can undermine the effectiveness of the tests. Mike Penning, the policing minister, said the "drugalyser" kits were approved by the Home Office last week for use in prosecuting motorists who drive while impaired by a range of illegal and prescription drugs.
"This is something that has plagued society for far too long," he said.
"People will have exactly the same view of drug-driving as they do of drink-driving: it is an abhorrent thing to do.
"Not only do you put your own life at risk, but you put innocent people’s lives at risk. We will drive this menace off the road.
"You won’t know if that constable at the side of the road is going to breathalyse you or if he is going to breathalyse you and drugalyse you. The answer is, do not drink and drive and do not take drugs and drive, whether they are legal or not."
Police chiefs and ministers fear that many people who take recreational drugs and drive think they can get away with it because the testing process is so cumbersome that it is not widely used.
Suspects taken to a police station for testing can escape prosecution if they claim to be unable to give a blood sample for religious or medical reasons, allowing time for the drugs to leave their bodies.
Driving under the influence of drugs is a significant cause of road accidents each year. Last year 921 people were hurt in 594 road accidents in Britain in which the driver or rider was impaired by legal or medicinal drugs. Of these, 36 people were killed and 241 injured seriously.
However, difficulties in obtaining evidence of drug use mean the true scale of the problem is likely to be far higher than official figures have shown. Ministers have estimated that drug-driving causes 200 deaths a year, but perpetrators are 50 times less likely to be convicted than drink-drivers.
Mr Penning, a Tory, said he had wanted to be able to act against drug-driving since he first encountered the effects it could have in his time working as a fireman, before he entered politics.
"We know that we have illegal drug use. Being impaired by taking medication or drugs or legal highs, if that impairs your driving ability, you’re going to cause accidents and kill people – and kill yourself. It is just the same as someone who is drunk," he said.
People taken to a station for testing "would claim that they had religious reasons or were haemophiliacs" or had other special reasons that meant they could not give a blood sample, he said. While they wasted time arguing, the drug was leaving their bodies.
"This will transform the ability of officers [in cases where] they know someone is impaired but breathalyse them for drink and find they have not got enough alcohol in their bloodstream to prosecute, but they’re still completely out of their tree.
"They will be able to do a saliva test at the roadside and a saliva test at the station."
Lillian Groves,14, was killed by a speeding motorist who had smoked cannabis
As with failure to complete an alcohol test, if motorists refuse repeatedly to take the drug tests, they will be prosecuted, he said.
The kits will be able to test for a range of substances, including so-called "legal highs" and medicines that cause drowsiness and should not be taken by drivers.
A new criminal offence of drug-driving" comes into force in March, and will be used to prosecute motorists found with quantities of drugs in their bloodstream above specified levels. Substances to be tested for include cocaine, heroin and cannabis, as well as some prescription painkillers, sleeping pills, and drugs used to treat anxiety.
Mr Penning said: "They won’t know what drugs we are looking for.
"The key is it’s not just about illegal drugs. If you go and get a prescription for strong painkillers it will say on there, ‘This may cause drowsiness, do not use heavy equipment and do not drive’.
"People sadly do, and then you have terrible accidents. We are not penalising motorists. We are trying to keep people safe, exactly as we do with drink."
Saliva testing kits will be sent to officers for use to speed up drug tests in police stations, and hand-held versions of the devices will be taken out in patrol cars for roadside tests, he said. The process of introducing the new equipment across the country is expected to begin this week.
Roadside saliva testing for drugs already takes place in Australia and Germany, but police have been awaiting Home Office approval for the equipment in Britain.
This was formally given last week and the kits are now officially deemed to be reliable and secure enough to provide robust evidence.
Several police forces began using saliva tests for cannabis only inside police stations earlier this year.
"When this is fully rolled out it will be exactly the same as drink driving," Mr Penning said.
"I will be telling chief constables to take this up as quickly as possible."
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