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Drug Driving

Drug Driving

Drug Driving

See here for the latest news about drug driving defences

Until 2015, drivers suspected of being under the influence of drugs whilst driving were required to take a Field Impairment Test. 


The Field Impairment Test included 5 fairly simple tests:

  • Pupil measure test
  • Romberg Test 
  • Walk and turn test 
  • One-leg stand test 
  • Finger to nose test 


The results of this were combined with the results from a test of blood/ or urine sample. Used to detect the presence of a drug or drug metabolite (a by-product of a drug). 

But, using this method made it difficult for the Crown Prosecution Service (CPS) to determine the level of impairment of the individual. Resulting in many ‘not guilty’ verdicts. 


Change within drug-driving legislation 

Due to this issue, legislation was widened. Now, motorists are subject to Section 5A of the Road Traffic Act. Which is an offence of driving. Where the individual has in fact or attempted to be in charge of a motor vehicle on a public road. In which the concentration of a specified drug in the blood was tested and results showed the concentration was above the limit prescribed for that drug. (Although no limits currently apply to urine samples). 

This legislation has proved very successful, in terms of prosecutions, in modern motoring law. That has resulted in almost 20,000 cases in 2020 alone. 


Which drugs are covered by the Regulations? 

There are 17 drugs (or their metabolites) that are covered by the regulations. Of which can be divided into two groups. 

  • Drugs that have widespread medicinal uses 
  • Drugs that do not have widespread medicinal uses 


Drugs that have widespread medicinal uses 

The limits for these drugs are set with the consideration of blood drug concentrations. At which concentrations, there is an increased risk of a road traffic collision. 

These include: 

  • Clonazepam
  • Diazepam
  • Flunitrazepam
  • Lorazepam
  • Morphine
  • Oxazepam
  • Temazepam
  • Methadone


Drugs that do not have widespread medicinal uses 

These drugs have no common medicinal use, therefore a ‘zero-tolerance’ approach to setting limits was adopted. This contrasts with the approach taken when setting alcohol limits. In which the limit was set at a point where the effect of alcohol would be expected to have impaired driving ability to a significant degree. 

These include: 

  • Amphetamine (can also be used medicinally)
  • Benzoylecgonine (a metabolite of Cocaine)
  • Cocaine
  • Delta-9-Tetrahydrocannabinol (THC)
  • Ketamine
  • Lysergic Acid Diethylamide (LSD)
  • Methylamphetamine
  • Methylenedioxymethamphetamine (MDMA or Ecstasy)
  • 6-Monoacetylmorphine (Heroin)

The process of Drug Driving testing 

The process begins at the roadside. Where an individual has been stopped by the police. Or where the individual has been involved in a collision/ accident which has resulted in police attendance. Officers will utilise a roadside testing device called ‘Securetec DrugWipe’. This test involves the collection of a swab from the individual's mouth. 

At present, the device will state the presence of: 

  • Cannabis (THC)
  • Cocaine and the Cocaine metabolite 
  • Benzoylecgonine (BZE)


A positive test will enable the arrest of the individual. Plus, the subsequent collection (if consented) of a blood sample, for laboratory testing. If this individual’s results for the stated drugs are over the limit, they will be charged. 

When the individual has used either Cannabis or Cocaine, in most cases, when this test is used, results are positive. Since the relics of drug use can be present for many hours and possibly days after drug use. 


What services Bericon can provide 

With an increase in the number of prosecutions, there has been an increase in the number of defenses being raised by corresponding individuals. 


Bericon can prepare court-ready reports in relation to: 

  • The consumption of drugs after driving. Providing a possible defense that the individual was under the limit when they drove 
  • The possibility of exposure to or ingestion of a drug unknowingly. That without exposure they would have been under the limit when they drove 
  • The possibility of being passively exposed to Cannabis smoke. Resulting in an elevated level of THC concentration in their blood


In cases of being ‘In charge of a vehicle’, the reports can also offer comments to:

  • The likelihood that a person’s drug level would have decreased below the legal limit when then drove 
  • The consideration of whether a medication (e.g. an antidepressant) or a medical condition could have caused an elevated reading 


Bericon can offer an expert review of analytics work undertaken by the Crown. This review will establish whether data has been correctly acquired, processed, and interpreted. To discuss drug driving testing, and or interpretation of results, please contact us.

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