Under the Road Traffic Act of 1988 it is an offence under section 4 for any person to drive or be in charge of a vehicle, whilst impaired through drink or drugs. Unlike in the case of alcohol consumption where there are statutory legal limits for the concentration of alcohol; in a drivers system, no such limits exist in the case of either illicit or prescription drugs. Where drugs and driving is suspected, the finding of a drug (licit or illicit) in a person's body fluids must be backed up by medical evidence of impairment, which could have been caused by that drug, However, just because a drug is present in a person's system doesn't mean that drug could or did cause the alleged impairment.
Person is stopped by police, due to alleged erratic driving behaviour and breathalysed at the roadside. The breathalyser test is negative, but the police arrest the driver on suspicion of being impaired through drugs. Driver examined by a doctor who suggests impairment. Driver blames poor driving and behaviour on being upset over a recent bereavement and denies being impaired. They admit to having previously consumed an antidepressant drug, but deny taking any for the last few days. They provide a sample of their urine, which is sent to the laboratory to be tested for drugs. Low levels of an antidepressant drug detected in the urine sample. Driver charged under Road Traffic Act with driving whilst impaired through drugs.
Our forensic drugs driving experts have considerable experience in the analysis of body fluids for drugs and the interpretation of the results of those analyses.