Why They Can't Make a Gadget to Test Cannabis DUI. Yet. - RxLeaf

Why They Can’t Make a Gadget to Test Cannabis DUI. Yet.

Jennifer Grant

The same technology used to detect alcohol DUI does NOT work for cannabis

A breathalyzer test is standard operating procedure for law enforcement officers in targeting and arresting drunk drivers. Determining the intoxication level of an individual under the influence of cannabis, however, is a more complicated process. There is currently no accurate gadget that can be used in the field. Further to that, breath, blood, or urine THC levels are no measure of intoxication. One person can take a very small amount and immediately get intoxicated, while another smokes a whole joint and only gets a buzz.

Cannabis bud, joint, and car keys in a pile against white background

Are you able to drive well while under the influence of cannabis?

What causes this difference? It all boils down to body mass index (BMI), consumption method (edibles take longer to clear), and how THC – the main psychoactive component in cannabis – is metabolized within the body. Some people, for example, consume cannabis several times a day for medicinal purposes and thus develop a tolerance to it. If such a person’s sobriety were to be questioned by police officers, THC levels may measure high, but intoxication levels would actually be very low.

If measuring intoxication by blood sample, it should be known that THC quickly leaves the bloodstream. Peak levels are reached at five to 10 minutes after inhaling. Following this, measurable levels start to decline quickly. The system is onto this, however, and now regularly tests for a metabolite of THC called THC-COOH; this peaks at 81 minutes. You should also be aware that THC re-enters the bloodstream from fat tissue when you are exercising or under extreme stress (ahem – being arrested).

Woman's feet walking line in DUI test

Field sobriety tests can be a better measure of competency to drive, including touching your nose and walking the line.

To combat all of these variables, law enforcement officers have come up with different methods of detecting intoxication. In addition to the standard observable measures of intoxication, they also work with drug recognition evaluators (DRE) who use twelve steps to evaluate intoxication. Some of the steps evaluated in the test are similar to the sobriety tests performed by law enforcement officers. DRE also ask individuals to touch their noses, close their eyes, or even to gauge when 30 seconds have passed.

It’s interesting to note that the ability to gauge time differs with different intoxicants. Meth speeds up time and users will usually say 30 seconds is up before it’s even half that. Cannabis consumers will drag on past 30 seconds, sometimes even reaching 2 minutes before they declare 30 seconds is up. The DRE also examines the size of pupils and how well the individual controls eye movement. Someone using cannabis has difficulty crossing their eyes (I know you’re trying that right now).   A blood pressure test, muscle response test, notes from interviews, and a urine test round up the DRE’s evaluation.

The main challenge is not in finding ways of measuring THC concentrations, but rather understanding how the various active compounds in cannabis affect the body and mind.  Even scientists do not yet fully understand how the compounds work, so this would all make for flimsy evidence in a court situation.

Perhaps there will be better and more accurate ways of detecting cannabis intoxication in future. In the meantime, stay safe out there and always have a designated driver of you’re going to be having a “big” night out.

Jennifer Grant

Jennifer is Editor in Chief for Rxleaf. She has been employed as a professional writer for over fifteen years. Jennifer graduated from the University of Guelph with an Honors Biological Science degree, majoring in the biomedical field.

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