Drug Driving Law

Drug driving will be dealt with differently after March 2105. Before that date it as an offence to drive whilst under the influence of drugs. In order to convict someone the CPS had to persuade the court that someone was unfit to drive and that this impaired their driving. This was not easy and few people were convicted of this offence. In order to show someone was under the influence the Police would do field impairment tests. The old forms directed the police to confirm what evidence there was that the driver might have been impaired by drugs.

Typically the police would put things like “dilated pupils, very agitated, mood swings”. They would then have to indicate which symptoms applied such as hyperactivity, drowsiness, eye pupils dilated, thirst, jaundice etc. They would then have to confirm which drug was suspected. A doctor was then required to undertake a field impairment test which involved doing checks such as getting a handwriting specimen, measuring pupil size and noting on a scale of 1 – 9.5, instructing the suspect to close their eyes, tilt head back and indicate when 30 seconds have passed, walking along an imaginary line, standing on one leg and touching their nose with their finger.


This is similar to how the police had to deal with drink driving before intoxylisers were introduced. The introduction of intoxylisers meant that a specific amount of alcohol could be detected in breath. A level of alcohol was then set and it was an offence to drive above that level. This level was based on what experts perceived to be an appropriate amount above which someone’s driving would be impaired.


A similar system has now been introduced for drug driving.

The Road Traffic Act has been amended to deal with Drug Driving. It will make it an offence to drive, or be in charge of a vehicle whilst over a specified limit for one of 16 drugs.

The drugs are as follows –

Benzoylecgonine – 50 µg/L

Clonazepam – 50 µg/L

Cocaine – 10 µg/L

Delta-9-Tetrahydrocannabinol – 2 µg/L

Diazepam – 550 µg/L

Flunitrazepam – 300 µg/L

Ketamine – 20 µg/L

Lorazepam – 100 µg/L

Lysergic Acid Diethylamide – 1 µg/L

Methadone – 500 µg/L

Methylamphetamine – 10 µg/L

Methylenedioxymethamphetamine – 10 µg/L

6-Monoacetylmorphine – 5 µg/L

Morphine – 80 µg/L

Oxazepam – 300 µg/L

Temazepam – 1000 µg/L


The Law is contained in Section 5A of Road Traffic Act 1988, the offence is driving or being in charge of a motor vehicle with concentration of specified controlled drug above specified limit.


The offences are set out in sub sections (1) and (2) –

(1) This section applies where a person (“D”)—


(a) drives or attempts to drive a motor vehicle on a road or other public place, or

(b) is in charge of a motor vehicle on a road or other public place, and there is in D’s body a specified controlled drug.


(2) D is guilty of an offence if the proportion of the drug in D’s blood or urine exceeds the specified limit for that drug.

This is similar to the drink driving law and creates three offences, driving, attempting to drive and being in charge of a vehicle whilst over the prescribed limit for a specified drug. Like the drink driving law it has to be on a road or other public place and public place is defined as somewhere where the public have access so includes car parks etc.


The specific drug driving defences are set out in Section 3. –

(3) It is a defence for a person (“D”) charged with an offence under this section to show that—

(a) the specified controlled drug had been prescribed or supplied to D for medical or dental purposes,

(b) D took the drug in accordance with any directions given by the person by whom the drug was prescribed or supplied, and with any accompanying instructions (so far as consistent with any such directions) given by the manufacturer or distributor of the drug, and

(c) D’s possession of the drug immediately before taking it was not unlawful under section 5(1) of the Misuse of Drugs Act 1971 (restriction of possession of controlled drugs) because of an exemption in regulations made under section 7 of that Act (authorisation of activities otherwise unlawful under foregoing provisions).


A number of these drugs are prescribed drugs or can be found in prescribed drugs. It is only right that the law allows a defence where the defendant can show that the drugs were prescribed or supplied to him or her. It is not enough to simply show that they were prescribed but that they were also taken in accordance with the instructions. Section (c) covers drugs that would have been unlawful to possess but are lawful through an exemption, this is not likely to arise often in practice.


(4) The defence in subsection (3) is not available if D’s actions were—


(a) contrary to any advice, given by the person by whom the drug was prescribed or supplied, about the amount of time that should elapse between taking the drug and driving a motor vehicle, or

(b) contrary to any accompanying instructions about that matter (so far as consistent with any such advice) given by the manufacturer or distributor of the drug.


A further condition is placed on the ‘Prescribed or supplied’ defence in that the drug must not be taken contrary to any advice given by the person supplying or prescribing the drug as to driving after taking the drug.


(5) If evidence is adduced that is sufficient to raise an issue with respect to the defence in subsection (3), the court must assume that the defence is satisfied unless the prosecution proves beyond reasonable doubt that it is not.


This is an assistance to the defence. Once evidence is supplied, such as a prescription then the prosecution must prove beyond reasonable doubt that this does not satisfy the defence. In reality if someone can show a prescription then it is unlikely that the prosecution will pursue the matter.


(6) It is a defence for a person (“D”) charged with an offence by virtue of subsection (1)(b) to prove that at the time D is alleged to have committed the offence the circumstances were such that there was no likelihood of D driving the vehicle whilst the proportion of the specified controlled drug in D’s blood or urine remained likely to exceed the specified limit for that drug.


This is the standard ‘in charge’ defence. If you can show you would not have driven until you were under the limit then you will have a valid defence. A common scenario for the alcohol equivalent is where someone is found asleep in their car and says they would not have driven for several hours. An expert report is normally required to show when they would have been under the limit. If accepted then the court will find the person not guilty.


(7) The court may, in determining whether there was such a likelihood, disregard any injury to D and any damage to the vehicle.


Again, similar to the drink driving provisions the court are not able to say that the person would not have driven simply because the car was damaged.


How will this work in practice?

It is expected that the  police will almost always test for alcohol first at the roadside as it is easier and coincidentally cheaper to do so. So the police will identify a driver that they suspect may be driving under the influence of drugs or alcohol. This may be because the driving is erratic or something as simple as not switching the headlights on. Often our clients tell us there were questioned by the police because they had been too cautious, for example they haven’t pulled away quickly enough from traffic lights etc. Once the police form a suspicion that the driver may be under the influence they will then stop the driver. If they still maintain the suspicion they will ask the driver to provide an alcohol breath test . If he fails the police will arrest him and require an evidential breath test at the station.


If the driver passes the breath test but the police still believe that he is under the influence then they will ask him to provide a mouth swab to test for drugs. If this is shown to be positive he will be arrested and taken back to the station and required to provide a blood test to confirm the type and level of drugs. He will be bailed as now for the blood to be analysed and charged if over the limit. The police retain the right to charge the driver with driving whilst under the influence of a drug. This would happen if he passed all the tests but appeared to be under the influence. He would then be required to take the impairment test as detailed above.

It is worth noting that there is no provision at present for urine tests for drugs, this is because it is accepted by all parties that current testing equipment does not provide accurate results for drug levels in urine.


If you have been charged with Drug Driving and want expert advice or representation from a Drug Driving Solicitor call now to speak to our highly trained team on 01623 600645.