How Stoned is Too Stoned to Drive?

Should States Set THC Limits for Marijuana DUI?

Several weeks ago, a law died in the California Legislature that would have made it significantly easier to go after drivers and prosecute them for marijuana DUI. The law aimed to set the limit at 2 nanograms of THC per milliliter of blood, criminalizing driving with only trace amount in the blood. This level would have been much lower than the 5 nanogram limit that several states have set, including both Colorado and Washington. However, marijuana advocates posit that any per se limitation similar to alcohol-related DWIs would be unfair and unreliable because THC remains in the bloodstream for days after using.

Marijuana and Driving is Becoming a Hotter Issue

There is a lot of debate regarding the impact marijuana can have on a person’s ability to drive. Some believe that marijuana has a very negative effect on driving, and poses as great of a danger as alcohol. And there is some evidence that ingesting marijuana results in the loss of peripheral vision. It can also affect balance and a person’s perception of the passage of time. However, even the federal government questions the exact relationship between using marijuana and impaired driving. On its website, The National Highway Traffic Safety Administration—the authority on impaired driving—says that:

“It is difficult to establish a relationship between a person’s THC blood or plasma concentration and performance impairing effects”

In a 2012 study referenced in this New York Times article, only 30% of people under the influence of THC actually failed the Standardized Field Sobriety Tests. Although hardly foolproof for alcohol, these tests have been shown to detect between 60-80% of people who have been drinking. Unlike alcohol, which fairly predictably impairs all drinkers—both new users and long-term alcoholics, there is no medical consensus about how marijuana will affect any particular individual. It is inevitable that more states will follow the lead of Colorado and Washington and legalize marijuana. As that happens and the availability increases, the number of high drivers will also increase, and this will be more of an issue in the coming years. Below is a discussion of the different marijuana DUI laws that states are adopting.

Different States, Different Marijuana DUI Laws

Every state in the country has laws criminalizing driving under the influence of marijuana or drugs. These laws are called DUID, which means driving under the influence of drugs. There are essentially three different kinds of DUID laws. (For a more in depth discussion of state DUID laws, see NORML’s state-by-state breakdown of drugged driving laws.)

1. Per Se Drugged Driving Laws

Per se laws ban the operation of a motor vehicle if the driver has more than a set limit of marijuana in their system. For instance, per se limits for alcohol (.08 grams of alcohol per 100 millimeters of blood) are enforced in all 50 states. The two states where marijuana is legal, Washington and Colorado, recently enacted per se limits. Other states such as Nevada, Utah, Pennsylvania, and Ohio have similar laws.

2. Zero Tolerance Per Se Laws

There are other states that have even stricter Marijuana DUI laws. As you might expect, something called “zero tolerance” would not be rehabilitative. In states such as Arizona, Oklahoma, and Georgia, driving with any amount marijuana in your system is illegal. One big problem with this is that THC can linger around in your blood for days and weeks. Under these laws, a person could get a DUI well after any impairing effects of marijuana have worn off.

3. Effect-Based Laws

There are effect-based DUI laws that require that prosecutors prove beyond a reasonable doubt that the driver recently ingested marijuana, and because of that, the driver could not safely operate a motor vehicle. In Texas, this means that the prosecution must show that you were operating a motor vehicle in a public place without the normal use of your mental and physical faculties.

If you are charged with any drug-related crime, including DUI, call me to set up an appointment for a free and confidential case evaluation. 817-689-7002. Our office is downtown: 108 Main Street, Fort Worth, TX, 76102