There are two main issues with current urine-based marijuana drug tests – adulteration and the length of detection time in comparison to the window of impairment.
Adulteration refers to an individual cheating on a urine test, which can be easily accomplished as the tests are generally not supervised by a third party. The subject can therefore purchase fake urine or use a clean sample from someone else to bypass the test. The adulteration issues are demonstrated by lower urine positivity rates for marijuana when compared to increasing positivity rates among saliva-based tests. In 2020, marijuana positivity increased only 16.1% for urine tests versus 35% for saliva-based tests. (18)
The length of detection time for urine is well past the window of impairment. This refers to the amount of time that marijuana is detected in urine and can range from a few days up to 30 days for marijuana (THC). The window of impairment, on the other hand, refers to the length of time marijuana’s psychoactive properties affects the user and creates a “high.” A comprehensive review of all impairment studies from Neuroscience & Behavioral Reviews suggests that cannabis impairment can last 3 to 10 hours, making urine-based testing ineffective and potentially unfair, especially in the 23 states that allow legal marijuana for recreational purposes as well as 38 states where medical marijuana is legal. (19) See (Fig. 1) below.