With no easy test, MO law enforcement looks for ways to combat marijuana-impaired driving

In less than a month, marijuana advocates will celebrate the one-year anniversary of recreational marijuana's legalization in Missouri. As implementation of the voter-approved legislation continues to roll out, there are aspects of the industry and enforcement that remain hazy — including how to handle marijuana consumers who drive under the influence.

Article 14 of the Missouri Constitution permits adults over the age of 21 to possess and consume marijuana and marijuana products, but adults are not allowed to use marijuana while driving a motor vehicle or drive while under the influence of marijuana. In Springfield, a municipal ordinance also prohibits adults from consuming marijuana in a motor vehicle that is parked in a public space, like streets and highways, transportation facilities, amusement parks, parking lots and playgrounds.

Although driving under the influence of marijuana is illegal in all states, the number of drivers who do so is growing. USA Today reported that between 2014 and 2018, the number of drivers who acknowledged driving under the influence of marijuana spiked 47%.

Marijuana affects each user differently, but it has commonly been found to slow reaction time, impair coordination and distort perception, according to the Centers for Disease Control and Prevention.

State, local entities limited to blood samples

As of October, the only way Missouri law enforcement can measure THC concentration in a driver's body, if the driver is pulled over for potential impairment, is through a blood sample, Greene County Sherriff's Office Captain Kenny Weatherford told the News-Leader.

All blood samples collected throughout the state of Missouri are sent to the Missouri State Highway Patrol crime laboratory. Results can take anywhere from weeks to as much as six to eight months, Weatherford said.

While the Springfield Police Department utilizes the MSHP crime laboratory, Public Affairs Officer Cris Swaters told the News-Leader that the department is not currently measuring THC concentration in drivers' bodies.

While breathalyzers are commonly used for measuring alcohol content in a driver's body, efforts to create a similar piece of technology for measuring THC levels have been largely unsuccessful. This is because the behavior of THC after ingestion is different from alcohol, according to a USA Today story about ElectraTect, an Arizona-based company working to create a marijuana breathalyzer.

What is the legal limit of THC while driving in Missouri?

A legal limit for how much THC someone can have in their body while driving has not been set in Missouri. MSHP Public Information Officer Michael McClure said this is because there is limited science that backs varying limits.

However, some states where recreational marijuana is legal have established legal limits. In Colorado, for example, drivers can be cited and arrested for impairment if their blood level indicates 5 nanograms or more of Delta-9 THC, according to the Colorado Department of Transportation. Delta-9 is the most common form of THC found in marijuana and marijuana-infused products.

More: Marijuana terms to know, now that Missouri has legalized weed

Twelve states, including Arizona, Delaware, Georgia, Indiana, Iowa, Michigan, Oklahoma, Pennsylvania, Rhode Island, South Dakota, Utah and Wisconsin, operate under zero tolerance laws, according to the National Conference of State Legislators. This means any amount of THC found in a driver's body can lead to a citation or arrest for impairment.

Expansion of highway patrol's Drug Recognition Experts program

In an effort to further prepare troopers for regulating marijuana-impaired driving, the Highway Patrol is looking to expand its Drug Recognition Experts program. McClure described the program as "rigorous" — as of Oct. 11, there were only 60 Drug Recognition Experts statewide.

These experts are trained to "determine whether observed driver impairment is due to drug use other than alcohol, and if so, to identify the category or categories of drugs inducing the observable signs of impairment," McClure said.

Curriculum for this project is divided into three phases. The first phase is conducted over two days and educates participants on techniques for drug evaluation. The second phase is a seven-day classroom program where participants learn more details about these evaluation techniques, including the physiology, effects of drugs and legal considerations. The third phase is the completion of a field certification. To learn certification, participants must evaluate subjects suspected of impairment other than alcohol.

Although the Drug Recognition Experts program is voluntary, McClure said all troopers must complete the Advanced Roadside Impairment Driving Enforcement course, which is meant to "bridge the knowledge and skills gap between standardized field sobriety testing at (Driving Recognition Experts)."

Greta Cross is the trending topics reporter for the Springfield News-Leader. Follow her on X and Instagram @gretacrossphoto. Story idea? Email her at gcross@gannett.com.

This article originally appeared on Springfield News-Leader: Missouri has yet to establish legislation around THC legal limits