Background
The defendant was stopped by police while driving and subsequently tested positive at the roadside for a cannabis-related compound. Due to a reported needle phobia, they were unable to provide an evidential blood sample, and a urine sample was taken instead.
Because the defendant was charged under Section 4 of the Road Traffic Act 1988 (“driving whilst impaired”), the prosecution was required to prove actual impairment, not just the presence of drugs. This placed a high evidential burden on the Crown and required a detailed specialist review of both the toxicology and the officer’s impairment assessment.
Bericon Forensics was instructed to provide an independent forensic evaluation.
Our Forensic Findings
1. Toxicology: No evidence of impairment
Our review of the urine toxicology demonstrated:
– The cannabis-related compounds detected were inactive metabolites, incapable of causing impairment.
– The results were consistent with historic use, possibly the day before the incident, as the defendant reported.
– Temazepam metabolites were present, aligning with his reported diazepam use, but no quantitative data was available to assess any pharmacological effect.
Crucially, the urine result alone cannot determine impairment, and in this case it provided no scientific support for the allegation that the defendant was impaired at the time of driving.
2. Legal Context: Absence of statutory limits
As the case fell under Section 4 (impairment) rather than Section 5A (statutory limits), the prosecution still had to show:
– Impairment in driving behaviour
– Impairment observed by officers/medical practitioners
– Drug concentrations capable of causing impairment
Because no active substances were detected and no quantification was available, one of the three pillars of impairment evidence was entirely absent.
3. Scrutiny of the MGDD/F Impairment Assessment
We analysed the behavioural observations made by the police officer:
– The defendant showed difficulty with the time-estimation task, but the officer’s account did not identify which other tests supported an opinion of impairment.
– No consideration was given to the defendant’s significant anxiety, despite their needle phobia and the stressful circumstances. Anxiety can affect many elements of a field impairment test, potentially mimicking drug-related behaviours.
Bericon’s expert conclusion was clear:
There was insufficient behavioural or toxicological evidence to support an allegation of drug-related impairment.
Outcome
Following submission of our report, the defence was able to challenge the reliability of the impairment evidence. As a result:
– The Crown accepted a plea to the far lesser offence of driving without due care, rather than drug-driving.
– The defendant received penalty points only, avoiding the mandatory disqualification associated with drug-driving offences.
Impact of Our Work
This case demonstrates the critical importance of expert toxicological interpretation in drug-driving cases, particularly those prosecuted under Section 4. By analysing both the laboratory findings and the officer’s impairment assessment, Bericon’s work revealed:
– that the toxicology did not support impairment;
– that key procedural and interpretative gaps existed in the police assessment;
– alternative explanations for the defendant’s behaviour were entirely plausible.
