Testing people for marijuana impairment by measuring THC levels is unreliable


A new study suggests that the amount of THC in a person’s body is not an accurate indicator of impairment.

Twenty participants took part in the study, which was carried out with the support of the National Institute of Justice. They were asked to consume cannabis in the form of edibles or vapes, all with different levels of THC. Then the participants were tested with standard field sobriety tests and asked to solve cognitive tasks.

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Photo by kaboompics via Pixabay

According to the results of the study, the amount of THC was not a reliable indicator when it came to the impairment of the participant. This is important as it challenges many of the rules and regulations regarding cannabis use, especially when it comes to driving impairments.

“These important findings are no surprise,” said NORML Deputy Director Paul Armentano. “Despite a handful of states setting THC limits per se as part of their road safety laws, there is no science to show that these arbitrary limits are reliable predictors of recent cannabis exposure or impairment.”

Investigating how marijuana affects the skills needed to drive safely, the researchers found that THC levels in bio-liquids did not correlate with field sobriety test performance or marijuana poisoning performance, regardless of how the cannabis was ingested . Read more:

– Natl Inst of Justice (@OJPNIJ) June 3, 2021

The researchers collected blood, urine, and mouth samples from participants who had ingested THC. The data did not correlate with the cognitive tasks and field sobriety tests that participants were asked to take. Some participants had low THC levels and performed poorly on these tasks, and vice versa.

THC has long been the focus of impairment when talking about marijuana use. Now that the drug is legalized in various states, this is a problem as it can lead to the arrest of people who should not be arrested. The available drug tests, especially those done in traffic, cannot measure the impairment. You can only tell if someone has ingested cannabis or not.

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Driving under the influence should be monitored as it can lead to dangerous situations. Still, it’s important to avoid problems when they don’t exist, especially since data shows that legalizing marijuana hasn’t resulted in an increase in car accidents.


Beth Edmonds