Cannabis drug testing describes various drug test methodologies for the use of cannabis in medicine, sport, and law. Cannabis use is highly detectable and can be detected by urinalysis, hair analysis, as well as saliva tests for days or weeks.
Unlike alcohol, for which impairment can be reasonably measured using a breathalyser (and confirmed with a blood alcohol content measurement), valid detection for cannabis is time-consuming, and tests cannot determine an approximate degree of impairment. The lack of suitable tests and agreed-upon intoxication levels is an issue in the legality of cannabis, especially regarding intoxicated driving.
The concentrations obtained from such analyses can often be helpful in distinguishing active use from passive exposure, elapsed time since use, and extent or duration of use. Although between 2000-2020 there had been a recall for 80% of at home drug testing kits. Because of this many companies took action and the industries identified the contents of these products which led them to take efforts of identifying the problem by finding a solution involving the chemical immunoassay. This was the main cause of why drug tests were so unreliable for the time being.
The Duquenois-Levine test is commonly used as a screening test in the field, but it cannot definitively confirm the presence of cannabis, as a large range of substances have been shown to give false positives.