Marijuana and the use of Cannabis have long been touted to offer certain health benefits for the immunocompromised and chronically ill, except it is still illegal in most of the world. Countries like the Netherlands, Jamaica, Costa Rica, Spain, and a few others have legalized the sale of recreational marijuana among rising public popularity. The main psychoactive component of cannabis is THC which produces the high sensation and can be inhaled or ingested. Users exposed to THC experience relaxing effects, including heightened sensory perception, euphoria, and an altered perception of time. THC can also be directly ingested, delaying the effects by more than 30 minutes. The effects of cannabis usually last up to 3 hours, although evidence of THC can remain in the body for days after initial use. 

Each person reacts differently to THC ingestion, but increased popularity and legalization around the world have contributed to concerns about its impact on driver safety. In the United States, more than 1.5 million people are arrested for driving under the influence each year. Studies in Colorado suggest an increase of marijuana-related DUIs by more than 48% last year, with an increasing trend over the last five years. The rising frequency DUIs is concerning because a large percentage may correlate with areas that have legalized marijuana. In recent years, the same study also identified increased frequency in marijuana-impaired drivers’ roles in deadly car accidents. 

Assessing impairment from a marijuana user is much harder than in individuals under the influence of alcohol. Despite recent increases in legalization and recreational use of marijuana, law enforcement has yet to identify an accurate and reliable test to determine a driver’s level of intoxication. The equivalent test for alcohol impairment is the breathalyzer test used to determine the blood alcohol content as it corresponds to legal limits. There are blood tests used for THC identification, but they do not provide an accurate assessment of an individual’s level of impairment because of the chemical’s varying effects with each person. New developments in law enforcement have focussed on creating behavioral tests to assess individual impairment, similar to methods used to confirm alcohol intoxication. 

Developing accurate tests is vital for driver’s safety and the ability of law enforcement to assess impaired individuals. Regular marijuana users have produced blood profiles that indicate stores of THC can remain detectable in the blood for 30 days in some cases. These THC levels are often higher than local DUI limits, even though the individual has not recently ingested marijuana. 

Factors impacting DUI statistics include regional THC blood limits, driving laws, past offenses, and law enforcement discretion. The consequences of driving under the influence are also different depending on the region but can implicate an individual up to a year in jail. 

Understanding the use of marijuana as it impacts drivers’ abilities and law enforcement methods for impairment detection are quickly becoming an increasingly vital area of research. Investments will continue to increase as recreational use becomes legalized in other parts of the world.