Drug Driving Success

Drug Driving Success

Drug Driving Success

Motorists are subjected to Section 5A of the Road Traffic Act. This is an offence where the individual has driven or been in charge of a motor vehicle with a concentration of specified controlled drug above specified its limit.

The Charge:

The Defendant was charged with Being in Charge of a Motor Vehicle when the Proportion of a Controlled Drug, namely tetrahydrocannabinol (THC), in their blood exceeded the Specified Limit.

Key Information:

– Police officers located the defendant in the driver’s seat of a parked motor vehicle.

– The defendant provided a roadside mouth swab sample which indicated the presence of a cannabis-related compound.

– The police arrested the defendant and took them to the station.

– They took a sample of the defendant’s blood for analysis.

– This sample was subsequently shown to contain tetrahydrocannabinol (THC) at a concentration of not less 2.2 microgrammes per litre (2.2µg/l). This concentration is above the statutory limit of 2µg/l.

– The defendant uses a cannabis “spliff” every day and last used cannabis the night before they were arrested.

– The defendant next intended to drive the following day.

Expert Instructions:

Bericon was instructed by the defendant’s solicitors to prepare a report that assessed the significance of THC being found in the defendant’s blood in relation to drug driving and, most significantly, when their reading could have fallen below the statutory limit.

Expert Findings:

The introduction of legislative limits means that individuals are charged based on whether they exceed them, which, for the case of THC is 2µg/l. Given that the defendant’s reading was not less than 2.2µg/l, they exceeded this limit.

The key question, however, was when this reading would have been below the statutory limit given that they had no immediate intention to drive.

Given the reported information about the defendant’s use of cannabis and the (THC) elimination from blood, the expert was of the view that it is possible that their reading could have been below the legal limit within a few hours of being tested. The expert is not able to associate a statistical likelihood of this being the case but it is a possibility.

However, the suggestion that the defendant is a regular user of cannabis did complicate the toxicological assessment of the case and it remained an unquantifiable possibility that his blood THC concentration would have taken longer to pass below the limit.

The Defendant was found Not Guilty.

To discuss drug driving cases, please contact us.


About the author
Following graduation in 1988, Alan took up employment as a forensic scientist and helped the organisation to develop into one of the leading UK forensic laboratories. He was promoted to Divisional Manager in 1997 and was responsible for all chemical analysis including forensic and drugs testing work, managing over 40 professional scientists and undertaking work...