Colorado Still Struggling With Marijuana Field Sobriety Tests

By Paul Gaita 07/09/19

Traffic fatalities involving drivers with marijuana in their system have risen as proper impairment testing continues to be an issue in the state.

woman getting pulled over in Colorado
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As Colorado marks the fifth anniversary of legalizing recreational marijuana, the problem of impaired driving—and how to properly test for impairment—remains as elusive as it was in 2014.

As an article in the Routt County daily newspaper Steamboat Pilot & Today noted, according to state law an individual is under the influence if more than five nanograms of THC is present in their bloodstream. But how to properly and legally test drivers remains out of the reach of police in the Centennial State, and users have expressed concern that if a method is discovered, they could test over the limit even if they are not legally impaired.

As a 2016-2017 report from the Substance Abuse and Mental Health Services Administration (SAMHSA) found, twice as many Coloradans smoke marijuana than residents of other states, and the number of adults in that demographic has risen since 2014.

Traffic fatalities involving drivers with marijuana in their system have also risen from 75 in 2014 to 139 in 2017. Statistics like these fuel the call for impairment testing, but the facts behind the latter data also underscore the challenges inherent to such a test.

The problem arises from the fact that the number of Colorado drivers involved in a traffic fatality who tested above the legal limit for THC has actually dropped, from 52 in 2016 to 35 the following year.

As Reason noted, this may be due to the fact that THC remains detectable in a user's system for up to 30 days, and drivers who test positive at the time of a crash may not, in fact, be legally impaired.

THC Lingers

As the Pilot & Today article stated, police are aware of this conflict. While field sobriety tests for alcohol impairment can be accurate at a rate between 91 and 94%, detecting marijuana impairment depends largely on blood tests.

"There is no go-to tool that is considered reliable across the board to determine if someone is impaired by marijuana," said former assistant district attorney of Routt County Matt Karzen in the article, who noted that most cases stem from a plea deal in which drivers plead guilty to driving while impaired, a traffic infraction which usually results in a fine and revoked driving privileges for 90 days—far less than a DUI conviction.

Marijuana advocates and law enforcement alike see this information as proof positive for more accurate means of measuring marijuana impairment, but efforts by lawmakers in Colorado have come up short; a bill proposed in 2019 would have empowered officers with the full right to determine impairment through a combination of field sobriety tests—observation and coordination tests—and blood testing. The bill was met with opposition and currently remains postponed until a February 2020 review.

5-Nanogram Limit

Legal representatives like Karzen and police officers have been encouraged to pursue impairment cases in which the individual is both clearly impaired—as the Pilot & Today noted, those exhibiting memory loss, poor driving or if marijuana smoke is evident. These signs, along with a blood test above the legal limit, are the best possible indicators at the moment for driving impairment.

"I'm very uncomfortable proceeding with a criminal prosecution on impaired driving based only on the five-nanogram limit," said Karzen.

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Paul Gaita lives in Los Angeles. He has contributed to the Los Angeles Times, Variety, LA Weekly, and The Los Angeles Beat, among many other publications and websites. 

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