The University of California San Diego conducted research to assess the effectiveness of field sobriety tests in detecting impairment caused by THC (tetrahydrocannabinol), the psychoactive component of cannabis, among drivers. Although these tests were able to differentiate between individuals who had consumed THC and those who hadn’t at specific time intervals, they may not be entirely reliable in definitively determining THC-specific driving impairment.
As cannabis legalization increases, road safety becomes a crucial concern, as the drug is known to impair crucial skills like reaction time, decision-making, coordination, and perception, which are vital for safe driving. The traditional correlation between blood alcohol concentrations and impairment is not directly applicable to THC blood concentrations and driving performance. Therefore, law enforcement relies on behavioral tests to gauge impairment, but these tests were originally validated for alcohol consumption and may not be entirely effective in detecting cannabis-related impairment.
In the study, researchers conducted a double-blind, placebo-controlled randomized clinical trial with 184 adult cannabis users. They were given either a placebo or THC cannabis cigarette, and highly trained law enforcement officers performed field sobriety tests on them at four different time intervals after smoking. The results showed that the tests could identify a higher proportion of THC consumers as impaired compared to the placebo group at three of the four time points. However, there was a significant overlap in poor test performance between the placebo and THC groups, leading to uncertainty in identifying THC-specific driving impairment solely through field sobriety tests.
The researchers suggested that while field sobriety tests are helpful in evaluating drivers, they may not be accurate enough on their own to determine THC impairment. Combining these tests with additional information, such as driver interviews and observation of driving ability, could improve overall accuracy in determining impairment caused by THC.
To further explore effective methods for detecting cannabis-impaired driving, the UC San Diego Center for Medicinal Cannabis Research plans to collaborate with the California Department of Motor Vehicles and the California Highway Patrol on a follow-up study involving 300 participants, starting in late summer 2023.
Table of Contents
Frequently Asked Questions (FAQs) about THC impairment
Question: What was the focus of the study conducted by the University of California San Diego?
Answer: The study aimed to evaluate the effectiveness of field sobriety tests in identifying driving impairment caused by THC, the psychoactive component of cannabis.
Question: How do field sobriety tests perform in detecting THC-induced impairment?
Answer: The field sobriety tests showed some ability to distinguish between individuals who had consumed THC and those who had not at specific time points. However, they may not be sufficient to definitively determine THC-specific driving impairment.
Question: Why are field sobriety tests used to gauge impairment in drivers under the influence of cannabis?
Answer: Unlike the correlation between blood alcohol concentrations and impairment, THC blood concentrations do not directly mirror driving performance. As a result, law enforcement relies on behavioral tests like field sobriety tests to assess impairment caused by cannabis.
Answer: Road safety is a critical concern as cannabis impairs essential skills required for safe driving, such as reaction time, coordination, decision-making, and perception. In California alone, there has been a 62% increase in fatal crashes involving drug-related impairment in recent years.
Question: What are the conclusions drawn from the research?
Answer: The researchers found that while field sobriety tests can be helpful in detecting THC consumption in drivers, they may not be accurate enough on their own to identify THC-specific impairment. Combining these tests with additional information, such as driver interviews and observation of driving ability, could enhance overall accuracy in determining impairment caused by THC.
More about THC impairment
- University of California San Diego
- JAMA Psychiatry
- California Department of Motor Vehicles
- California Highway Patrol
English 
Español 
Русский 
Deutsch 
Français 
Português
4 comments
Cali Uni study sayin’ tests sorta work detectin’ pot drivers. Not totally sure tho. High time for better ways to spot THC drivers, man!
Interesting research from UC San Diego on field sobriety tests & THC drivin’ impairment. Tests showin’ some promise, but more needed, ya feel me?
dude, this study lookin’ at pot impairin’ drivers, like duh! Sobriety tests doin’ ok spotin’ THC users, but not 100%, lolz!
wow, study from cali Uni, checkin’ if sobriety tests can find pot drivers. Resultz sayin’ tests kinda work, but not super sure ’bout it, ya know?