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Drug driving law

What drugs are illegal or medicinal?

In March 2015 a new drug driving law was introduced in England and Wales.

The new rules set 'zero tolerance' limits for 8 illegal drugs and 'risk based' limits for 8 prescription drugs estimated to be included in 19 million prescriptions every year.

Under the new (additional) offence the police need only obtain a blood sample and show that any of the specified drugs are present above the specified limit.

What's covered and what are the limits?

'Illegal' drugs
  • Benzoylecgonine 50µg/litre of blood
  • Cocaine 10µg/litre
  • Delta-9-tetrahydrocannibinol (cannabis) 2µg/litre
  • Ketamine 20µg/litre
  • Lysergic acid diethylamide 1µg/litre
  • Methylamphetamine 10µg/litre
  • MDMA 10µg/litre
  • 6-monoacetylmorphine (heroin) 5µg/litre
'Medicinal' drugs
  • Clonazepam 50µg/litre of blood
  • Diazepam 550µg/litre
  • Flunitrazepam 300µg/litre
  • Lorazepam 100µg/litre
  • Methadone 500µg/litre
  • Morphine 80µg/litre
  • Oxazepam 300µg/litre
  • Temazepam 1,000µg/litre
  • Amphetamine 250µg/litre



The limits are higher than normal prescribed doses which means that you will be able to drive as normal, so long as:

  • you are taking medicine in accordance with the advice of a healthcare professional and/or as printed in the accompanying leaflet, and
  • your driving is not impaired


What should I do?

If you are taking any of the specified 'medicinal' drugs:

  • Don't stop taking your medicines, prescribed or otherwise.
  • Iif you're not sure if you are safe to drive, check with your pharmacist or doctor.
  • Always follow the advice of a healthcare professional and read the accompanying leaflet.
  • Look out for new information which is starting to appear on the label and in patient information leaflets for medicines covered by this new regulation and for other similar medicines which may be picked up in testing.
Medical defence

There will be a medical defence if you have been taking medication as directed and are found to be over the limit, but not impaired.


The offence of driving while impaired by drugs remains.

If the police stop you and suspect that your driving may be impaired by drugs they can assess your capability to drive using a series of field impairment tests (pupil dilation, counting out loud, walking in a straight line etc.) and must prove, through a subsequent blood test, that drugs have caused any impairment observed.

AA comment

The AA fully supports the new offence, which will enable more effective law enforcement and help to keep our roads safe.

In fact, the AA has been campaigning for years to tighten up enforcement of drug driving, starting with a round table organised with the Home Office, police, Department for Transport, and medical and addiction experts in 2008.

Ultimately the success of this new offence will be down to police enforcement, education and resources.


(Page updated 22 March 2016)