Drivers face prosecution if they exceed limits set for the presence of eight illegal drugs, including cannabis and cocaine, and eight prescription drugs, including diazepam and methadone.
The new rules run alongside existing laws which make it an offence to drive when impaired by any drug.
A spokesman for Derbyshire police said: “The effects of drink-driving are well-known but getting behind the wheel while under the influence of drugs is just as dangerous.
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“This change to the law makes it an offence to drive with illegal drugs and certain legal medicines over a specific level.
“Taking even a small amount of an illegal drug could put a driver over the limit.
“Having the ability to test drivers at the roadside and pursue convictions if people test positive means that we can continue to make roads across Derbyshire as safe as we can.”
Road safety minister Robert Goodwill said: “This new law will save lives.
“We know driving under the influence of drugs is extremely dangerous – it devastates families and ruins lives.
“The Government’s message is clear – if you take drugs and drive, you are endangering yourself and others and you risk losing your licence and a conviction.”
For more information about the new laws, visit HERE