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Is legalizing marijuana leading to more DUIs?

There's a complicated relationship between rates of marijuana use and DUIs, but one thing is certain: Driving under the influence of any substance is reckless.

In recent years, a slew of states have legalized recreational marijuana including Washington, Oregon, California, Alaska and Colorado.

Medical marijuana is legal in 26 states, the District of Columbia and Guam, plus popular opinion on marijuana has also grown more positive.

Not including tobacco and alcohol, marijuana is the most used drug in the United States according to the 2013 National Survey on Drug Use and Health.

But this steady uptick in marijuana consumption has legislators and state departments of transportation worried about rates of driving under the influence of marijuana, which has been scientifically shown to be dangerous.

While the data shows a complicated relationship between rates of marijuana use and DUIs, one thing is certain: Driving under the influence of any substance is reckless, and creating awareness and deterrence through sensible legislation and education will make everyone on the road safer.

States' differing approaches to marijuana and DUIs

Because of the unique construction and balance of power in the United States, states are free to create laws that may not align with the federal government.

This system has led to states like Colorado, Oregon and Alaska creating different training programs for law enforcement to recognize high driving. They’ve also created different regulations about how much of the psychoactive substance in marijuana — THC — can be legally present in someone's blood when they’re operating a vehicle in an attempt to replicate alcohol DUI regulations.

Washington and Colorado allow the lowest level of THC to be present in the blood. Any more than 5 nanograms per milliliter of THC found in a blood test can result in DUI prosecution.

However, because the human body processes THC differently than alcohol, scientists say the amount of THC in someone's blood is not a reliable predictor of how impaired someone is, creating problems for both proving the extent to which marijuana factors into accidents and establishing regulations.

Washington's cautionary tale

After marijuana was legalized in Washington in 2012, the AAA analyzed crash data before and after to determine whether any correlation between legalization and DUI rates existed.

Before marijuana was legalized, 8.3 percent of drivers involved in fatal car crashes had traces of THC in their blood. After, the amount was 17 percent. The total number of crashes went up by a small amount.

However, since the initial bump in crashes, Washington's law enforcement has noticed the crash rate has stabilized and DUI rates have remained unchanged.

"The Washington State Patrol's numbers indicate that, despite the legalization of recreational marijuana, driving under the influence (DUI) has not measurably increased... Some people drove impaired on marijuana before legalization, and about the same number will do so after legalization," said King County Sheriff John Urquhart in 2015.

Education curbing DUIs

The bump in crashes following marijuana legalization in states like Washington has led other states to prevent this course of events with awareness campaigns.

When Colorado voted to legalize recreational marijuana in 2014, the legislature took a preemptive strike with ad campaigns designed to increase awareness about driving while high.

"Colorado State Patrol reported that from January to March of 2017, 155 people were cited for marijuana-use-only impairment while driving, compared to 232 cited from January to March of 2016. The number of citations noting combined alcohol and marijuana use also declined," according to the Colorado Division of Transportation.

Ad campaigns and measures to increase awareness may have contributed to Colorado's drop in the number of people arrested for driving under the influence of marijuana this year.


In total, states that have increasing medical and recreational marijuana consumption still have research to do to create effective DUI parameters.

Almost no hard data supports that legalizing marijuana leads to more DUIs in a state long term, but states still need to be proactive about enacting measures to curb driving under the influence.

What the data shows more clearly is that the combination of smart legislation and public education can have positive results.

Renys was founded in Damariscotta, Maine over 65 years ago and today has 17 store locations in Maine. This state isn’t just home to our stores though — it’s home to our customers, our employees and our families. We care about them and the well-being of everyone in our community, so we invite you to commit to quit distracted driving and take the Drive Safe Maine Pledge. We love the excitement of a Maine adventure, but the excitement of car crashes is something we can all do without. See contest rules here or apply in the sidebar on the Drive Safe Maine page.

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