Marijuana Legalization: How Does It Affect DUI/DWI Law?

The impact of the decriminalization of pot on state DUI/DWI laws.

In November 2016, voters in four states—California, Nevada, Massachusetts, and Maine—approved ballots measures decriminalizing recreational marijuana use. When the new laws go into effect, there will be a total of eight states, plus Washington D.C., where adults can legally use and possess pot without a prescription. (Voters have also now approved medical marijuana in 28 states and the District of Columbia.)

So, how does the legalization of weed affect state DUI/DWI law?

Generally, it has no effect: Most states that have decriminalized marijuana haven’t changed their DUI/DWI laws.

(Find out more specific information on how state DUI laws cover stoned driving.)

Per Se and Impairment DUIs

In most states, there are two types of DUI charge: “impairment” and “per se.” The difference between the two charges is how the prosecution proves the driver was “under the influence.”

With a per se DUI, the prosecution just needs to show that the driver had a blood alcohol concentration (BAC) of .08% or more. The thinking is that anyone who has a BAC of at least .08% is under the influence and shouldn’t be driving. But most per se laws refer only to alcohol concentration—they don’t prohibit driving with a certain amount drugs in your system. So, a motorist who is under the influence of only marijuana typically can’t be convicted of a per se DUI.

Impairment DUI charges, on the other hand, do apply to marijuana use. The focus of impairment laws is on how the drugs or alcohol affected the driver—not on which substance or the actual amount in the driver’s system. And, if the driver is impaired, it doesn’t matter whether the alcohol or drug use was legal. That’s why states haven’t had to change their DUI/DWI laws in the wake of marijuana decriminalization: A driver who ingests marijuana legally—but is impaired—can still be convicted of an impairment DUI.

(To learn more about the two types of DUI charge, see What’s the Difference Between Per Se and Impairment DUIs?)

PROVING IMPAIRMENT

All jurisdictions have an impairment DUI charge. But the degree of impairment the prosecution must prove to get a conviction varies by state.

In Nevada, for instance, prosecutors must prove the defendant, as the result of the drugs or alcohol ingested, was impaired “to a degree that [rendered him or her] incapable of safely driving or exercising actual physical control of a vehicle.” And under Massachusetts law, a person is “under the influence” if the substance ingested by the person “diminished the [person’s] ability to operate a motor vehicle safely.” (Nev. Rev. Stat. Ann. § 484C.105 (2016); Com. v. Connolly, 394 Mass. 169 (1985).)

Check with a local DUI attorney to find out the standard in your state.

“Per Se Marijuana” DUIs

A handful of states have adapted the per-se-DUI concept to drugged driving. In these states, motorists can be convicted of a per se drug DUI for driving with a certain concentration of drugs in their system. Two of the states that legalized recreational marijuana use—Nevada and Washington—have a “per se Marijuana” DUI charge.

Washington added a per se marijuana provision to its DUI law when it legalized marijuana in 2012. The provision prohibits driving with a concentration of five nanograms or more of THC (the primary psychoactive ingredient in marijuana) per milliliter of blood. Nevada, on the other hand, had a marijuana per se law prior to when voters decriminalized marijuana in November 2016. Nevada’s law makes it illegal to drive with two or more nanograms of THC per milliliter of blood or ten or more nanograms of THC per milliliter of urine. (Wash. Rev. Code Ann. § § 46.61.502(1), 46.61.506(2) (2016); Nev. Rev. Stat. Ann. § 484C.110 (2016).)

Talk to a DUI Attorney

The consequences of a DUI conviction are serious, and DUI law varies by state. If you’ve been arrested for or charged with driving under the influence, get in touch with an experienced DUI lawyer. A qualified DUI attorney can explain how the law applies to the facts of your case and help you decide on the best course of action.

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