“In theory‚ any person caught with even traces of marijuana in their system whilst driving can currently be arrested and/or prosecuted. But because it can remain in a person’s bloodstream for hours to days after use‚ a person who tests positive for marijuana isn’t necessarily intoxicated. At present‚ no limit has been established to determine how much THC needs to be present in the bloodstream for a person to be considered intoxicated‚” said Evans.
He said the likelihood of a driver being tested for drugs in a roadblock were minimal due to a lack of testing equipment available to officers.
“As a result‚ drivers that indulge in substances such as marijuana are less concerned with being caught in a roadblock than if they have consumed alcohol‚” Evans added.
THC can be detected in blood tests‚ urine tests and saliva tests – the latter producing results within three to five minutes.
“It is likely that legalisation of marijuana will only increase the number of active users driving a vehicle while under the influence. Until regulations are in place‚ however‚ it will be extremely difficult, if not impossible, to prove actual intoxication and there will be little to stop these drivers from taking to our roads‚” said Evans.