THC Tests Do Not Measure Impairment: Let’s End the Practice and Support Our Veterans

Lobbyist update:  The General Assembly is focused on the budget so it will likely be July before any cannabis bills are considered in committee or the possibility of a Senate vote. We are working to change S711 language so 1) physicians decide the medical conditions, dose, and delivery system and 2) ensure there is content labeling. Cannabis corporations recognized the progress NC NORML has made, and has hired lobbyists so the landscape has become more complicated. 

The reality is that bills without bipartisan sponsors aren’t likely to be heard. We will keep you posted with any changes. Your legislators still need to hear from you. 

Please send the following to your Representative and Senator in the NCGA (


Dear Senator or Representative: (insert name),

The National Highway and Transportation Safety Administration states that blood and urine tests are inaccurate to determine cannabis impairment. THC concentrations peak approximately 9-30 minutes after the start of smoking lasting 1-2 hours. “It is inadvisable to try and predict effects based on blood THC concentrations alone, and currently impossible to predict specific effects based on THC-COOH concentrations.” Detection of total THC metabolites in urine “is well past the window of intoxication and impairment.”  Detection can last more than 5 weeks in urine and low concentrations of THC have also been measured in over-the-counter hemp oil products.

National Highway and Transportation Safety Administration - Drugs and Human Performance Fact Sheets


Two other chemical tests have the same limitations as a blood test: they measure cannabis use within weeks, but don't test impairment. THC passes from the bloodstream into saliva, meaning that the test has the same limitation as blood tests, in that it doesn’t test impairment.  Breathalyzers and saliva tests as with the other chemical tests are not accurate measures of impairment.

Marketplace - Legal marijuana creates an industry for new breathalyzers


Since the chemical tests don't accurately test impairment, NC should require a more accurate impairment test.


A Canadian report evaluated the use of Drug Recognition Evaluators (DREs) and Standardized Field Sobriety Tests (SFSTs) for cannabis impairment. DREs/SFSTs perform poorly when tested under controlled conditions, thus neither would satisfy basic requirements of accuracy for any physical or behavioral test. Although DREs and SFSTs are subjective evaluations, they do attempt to test impairment.  CANNABIS USE AND DRIVING: Evidence Review. Coupled with a body camera the DRE/SFST could be an accurate record of impairment.

Sincerely, [Your Name] 

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If you have personal relationships with any of the lawmakers, please email [email protected] to work on a meeting.


Join NC NORML at the Southern Atlantic Hemp & Arts Expo next weekend for more info. 

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