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Field Sobriety Tests and THC Levels Unreliable Indicators of Marijuana Intoxication

NCJ Number
300292
Date Published
April 2021
Annotation

This Web article examines how cannabis dosage and administration method (eaten or vaped) affect THC levels in the body and how THC levels correlate with performance on impairment tests.

Abstract

Laws regarding driving under the influence of marijuana vary from state to state, with a growing trend toward “per se” laws that identify a level of delta-9-tetrahydrocannabinol (THC, one of the psychoactive substances in marijuana) in biofluids as a determinant of intoxication. However, there is little evidence correlating specific THC levels with impaired driving, making marijuana per se laws controversial and difficult to prosecute.

NIJ-supported researchers from RTI International examined how cannabis dose and administration method (eaten or vaped) affect THC levels in the body and how THC levels correlate with performance on impairment tests. RTI concluded that THC levels in biofluids were not reliable indicators of test performance or marijuana intoxication.