Drug Driving

Drug Driving – Offence codes: DR80/DR90

You will be understandably concerned if you have been charged with a ‘drug driving’ offence i.e. ‘driving whilst under the influence of drugs’. The rules governing drug driving offences are very similar to those applicable to drink drive offences. Convictions for drug driving offences include a ban from driving for significant periods of time, a large fine and sometimes imprisonment.

Drug Driving Legislation

There have been highly significant changes in this area of the law in recent years. There are numerous drugs specified under the drug driving legislation. Many are controlled substances in any event, such as heroin, cocaine and cannabis. If these drugs are in your system and above a prescribed level in your system whilst you are driving, the you will be committing an offence. Also, if these types of drugs are present and are proved to have impaired your ability to drive, then you will have also committed a drug driving offence.

​Controversially, recent changes to legislation now mean that you can commit a drug driving offence if you have been prescribed certain medications by your doctor, and you are found to be unfit to drive as a result of those drugs being in your system. If this is the case then you will also be guilty of a criminal offence. The question is whether you are fit to drive. Put another way, you are at risk of a conviction for drug driving if you get behind the wheel when you are impaired by the effects of the drugs taken. It can often cause considerable problems for the Prosecution to show that your driving was impaired as a result of the drugs in your system.

The laws regarding drug driving have recently changed and you could be affected – click here to find out how.

Table of Drugs and Driving Limits


 ‘Illegal’ drugs (‘accidental exposure’ – zero tolerance approach)  Threshold limit in blood
 benzoylecgonine (ecgonine benzoate)[main metabolite of cocaine]  50µg/L
 cocaine  10µg/L
 delta-9-tetrahydrocannibinol (cannabis)  2µg/L
 ketamine  20µg/L
 lysergic acid diethylamide (LSD)  1µg/L
 methylamphetamine (Crystal Meth)  10µg/L
Methylenedioxymethamphetamine (MDMA)  10µg/L
 6-monoacetylmorphine (Heroin)  5µg/L
 ‘Medicinal’ drugs (risk based approach)  Threshold limit in blood
 amphetamine (regulations were recently laid with the proposed limit and expected to come into force after 2 March 2015) 250µg/L
 clonazepam  50µg/L
 diazepam  550µg/L
 flunitrazepam  300µg/L
 lorazepam  100µg/L
 methadone  500µg/L
 morphine  80µg/L
 oxazepam  300µg/L
 temazepam  1,000µg/L


The first question we will ask on your behalf is whether the substance you have consumed is a drug for the purposes of the relevant legislation. It has been held by the Courts that a substance used as a medicine is a drug. A medicine is defined as “something to cure, alleviate or assist an ailing body”.

The prosecution must go on to prove beyond reasonable doubt that not only has a Defendant’s driving been impaired, but must also show that it was the drug that caused the impairment. Of course, different drugs have differing effects on the human body. People also react in various ways to drugs. It is therefore dangerous to rely upon generalised assertions about whether a drug will have had a particular impact on a Defendant. We would often recommend that you obtain your own expert evidence on these issues. In the absence of a breathalyser type test at the moment, the Police must administer a ‘Field Impairment Test’ where they test for impairment by observing you whilst you carry out a series of five tests:

  1. The Pupil Measure Test: testing the size of your pupils;
  2. The Romberg test: testing balance and judgement;
  3. The Walk and Turn test;
  4. The One Leg Stand test; and
  5. The Finger to Nose test.


Roadside and Blood Testing

The position is about to become far more complicated in this respect. The government plans to introduce a ‘drugalyser’ device at the roadside, which will be used to test your saliva for the presence of drugs like cannabis. Watch this space.

If you fail the roadside test, you will be taken to a police station and asked to consent to giving a sample of blood or urine. You should be given the opportunity to take a blood sample for yourself. We would strongly suggest that you have this tested as soon as possible, to avoid allegations of contamination or degradation of the quality of the sample. Failure to provide a sample, absent of a reasonable excuse, will result in a prosecution.

The allegation of drug driving is an extremely serious one and could lead to a custodial sentence and/or a mandatory disqualification from driving. For this reason, we would always recommend you get some specialist legal advice at an early stage so that you do not have your driving licence revoked.

Although a disqualification from driving is usually mandatory following a conviction for drug driving, it is sometimes possible to argue ‘special reasons’. If you can successfully argue ‘special reasons’, then it allows the Court a discretion as to whether to impose a driving ban. Good ‘special reasons’ arguments can include shortness of distance driven, driving in an emergency, or that you have taken drugs unknowingly. For further information about ‘special reasons, please click.



I and my whole family would like to express our utmost gratitude to the way you have handled this matter. I must confess that the outcome was well beyond our expectations (if not miraculous!)…..From the outset…….both of us just regained our confidence.Throughout the mitigation, I just felt this is someone who has really understood my plight and standing in my shoes. Again, I thank you very much.”

MR JJ: Failing to provide a specimen of breath

If you have any questions about drug driving, or if you face a drug drive related allegation and would like to prevent having your driving licence revoked, please call us on 0800 0126039 for a free and without obligation chat with an expert, or make an enquiry online.