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From seed to smoke: Driving under the influence

By Lucian McMahon  |  October 25, 2017

Verisk explores the marijuana DUI riskEditor's Note: This is a condensed version of the fourth article in our series on recreational and medical marijuana, From seed to smoke: Risks across the marijuana supply chain. Learn how ISO Emerging Issues subscribers can read the full article here.

Recreational marijuana

Marijuana is a type of plant that, if consumed properly, can give the user a “high,” generally induced by the psychoactive chemical THC.

In nine states and DC, so-called “adult,” “personal,” or “retail” marijuana and marijuana-related products may be used for non-medical (“recreational”) purposes, subject to certain limitations. Additionally, states typically enforce restrictions on driving under the influence of marijuana.

Medical marijuana

Additionally, in many states, so-called “medical marijuana” and/or marijuana-related products may be purchased and used for medicinal or therapeutic purposes, subject to certain limitations. An additional 17 states have so-called “limited access” medical marijuana programs, which the NCSL defines as programs that permit the use of “low THC, high cannabidiol (CBD)” products "in limited situations or as a legal defense.” These programs tend to be more restrictive than their comprehensive counterparts.

Marijuana use and ‘stoned’ driving

Marijuana and marijuana-related products that contain THC are intoxicants. It therefore stands to reason that marijuana use may impair driving abilities.

Some studies have found that marijuana use is correlated with an increase in the frequency and severity of car accidents. But not all studies show the correlation between marijuana use and a more frequent and severe risk of car accidents. There have been studies that point out that epidemiological complications make it difficult to know when marijuana is to blame for an accident.

This is largely due to the nature of marijuana intoxication itself. The length of a user’s intoxication from marijuana varies widely by consumption method, potency of the product, and the user’s physiological characteristics, according to AAA. Smoking may induce immediate onset of intoxication, with intoxication lasting several hours; oral consumption may induce intoxication as long as two hours after ingestion, with longer-lasting intoxicating effects.

Identifying marijuana intoxication is further complicated by THC’s persistence in a user's body for long periods after intoxication.

Marijuana limits vary by state

Different states that permit marijuana use may regulate driving under the influence in different ways.

Some states that allow marijuana use enforce so-called per se drugged driving laws, establishing a maximum allowable limit of THC in the bloodstream of a driver. For example, Washington State enforces a limit of 5 nanograms per milliliter of THC in a user’s bloodstream; amounts detected above that limit could constitute an offense of driving under the influence.

But some have reportedly argued that this limit is low enough to implicate regular medical and recreational users of marijuana because of THC’s potentially long persistence.

Other states, such as Oregon, do not enforce a per se limit; instead, Oregon law requires police officers to base their determination of a drugged driver on observations, apparently in response to the complications of detecting quantifiable marijuana intoxication.

The ISO Emerging Issues team continues to research and track potential considerations related to marijuana. You can find more of our research here.

Lucian McMahon, CPCU, ARM-E, AU-M, is a product development specialist with the ISO Emerging Issues team. You can contact Lucian at