New methods for drug driving detection

There is a growing road safety risk from the use of drugs whilst driving. Proving that a drug-driving offence has taken place can be complex and currently requires a blood sample to be taken from the driver and then tested in a lab.

An independent panel of experts, including those from King’s Forensics, have now determined that blood samples may not be the only way to detect whether a drug driving offence has taken place. Kim Wolff, Professor of Addiction Science at King’s College London, chaired the panel, which also included Professor David Cowan.

Drug concentrations in blood provide an accurate picture of the amount of drugs present in the body at the time of sampling and therefore are the strongest scientific evidence of impaired driving performance due to drugs.

However, the panel stated that the use of saliva samples (oral fluid) could help to reduce the time lag between the driving incident and the drug concentration test. Saliva sampling requires no medical personnel, meaning samples could be collected at the roadside in some cases. This would ensure that drug concentration data is more reflective of levels at the time of the driving incident.

Whilst whole blood is still considered the ‘gold standard’ for evidence, saliva samples could also prove particularly useful for illegal drugs known to decrease rapidly in blood after use, such as cocaine and heroin.

The experts suggested that saliva collection testing devices should have data on the volumes of saliva sampled and on the device’s precision to allow data to be used in criminal trials. Sample storage and transportation should also be controlled and monitored, with minimum standards for sampling kits.

In addition, the panel highlighted that the use of alcohol alongside any other controlled drugs would significantly increase the risk of a road traffic collision. They suggested that adjustments to the drug-driving legislation may need to be made to reflect this increasingly common behaviour, particularly the combination of cannabis and alcohol, using multiple drugs and the growing use of substances such as MDMA and Ketamine.

Read the panel’s report here.