Drug driving

Posted by Tim Williamson on
Have you been charged with "drug driving"?
Have you been charged with "drug driving"?

From 2 March 2015 the law on 'drug driving' changed.  The existing offence of driving whilst unfit through drugs remains but is now rarely used because that offence required the police to prove the driver was impaired.  The new offence of "drug driving" means that it is now illegal to drive if you have certain levels of certain drugs in your blood even if your driving is not impaired.

This has understandably led to an increase in arrests and convictions of many motorists.  The offence does not take into consideration the quality of a person's driving.

There is a potential defence as long as a motorist can prove the following:

  1. You have taken a prescribed medicine in accordance with your GP's instructions; and
  2. You have been told that you can drive under the prescribed dosage. 

If your driving was found to be impaired as a result of taking a prescribed drug you can still be prosecuted for driving whilst impaired through drugs, which has no medical defence available.


The penalty for the offence is a mandatory disqualification period of at least 12 months as well as a fine / community penalty or even a custodial sentence up to 26 weeks in the most serious cases.  A motorist convicted of a drink drive offence within the preceding 10 years will receive a mandatory 3 year driving ban.  Please see link to the substances affected.

Illegal Drugs (Accidental Exposure - Zero Tolerance Approach Threshold Limit in Blood 
Delta 9 Tetra Hydro Cannibinol (Cannibis) 2 mg/L
Kettamine 20 mg/L
Lysergic Acid Diethylamide 1 mg/L
Methylamphetamine 10 mg/L
MDMA 10 mg/L
Heroin  6 mg/L
Monoacetylmorphine 5 mg/L
Medicinal Drugs - Risk Based Approach            Medicinal Drugs - Risk Based Approach           
Amphetamine 250 mg/L
Clonazepam 50 mg/L
Diazepam 550 mg/L
Flunitizepam 300 mg/L
Lorazepham 100 mg/L
Methadone 500 mg/L
Morphine 80 mg/L
Oxazepam 300 mg/L
Temazepam 1000 mg/L

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Tim is a leading Criminal and Regulatory lawyer, who defends businesses and individuals under investigation by the police and regulatory bodies and when accused of criminal offences.

Tim Williamson
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