Why Marijuana Testing Still Matters
As more states legalize marijuana for medical or recreational use, many small business owners are asking an important question: should marijuana still be included in workplace drug testing programs? The answer is yes – but it requires thoughtful policy design and clear communication.
One of the biggest challenges with marijuana testing comes down to basic chemistry. Marijuana’s active psychoactive compound, THC, is fat soluble, while things like alcohol is water soluble (off-duty use of the substances are often compared, if not in actuality comparable). This difference plays a major role in how each substance behaves in the body and how long it can be detected. Because THC is fat soluble, it is stored in the body’s fatty tissues and released slowly over time. This means THC metabolites can remain detectable in the body for days or even weeks after marijuana use, especially with repeated and/or heavy use. In contrast, alcohol, being water soluble, moves through the bloodstream and is eliminated from the body much more quickly.
There is no universally agreed-upon or scientifically supported level of THC in the blood that reliably proves impairment. Unlike alcohol (which has a consistent blood alcohol concentration or BAC limit), an individual's response to THC varies significantly based on factors like tolerance, frequency of use, and method of consumption.
Even though marijuana testing is complicated by how THC is processed in the body, marijuana use can still affect reaction time, attention, judgment, and coordination. These effects matter particularly in safety-sensitive roles, such as driving, operating machinery, handling equipment, or performing tasks that require focus and quick decision-making. There have been studies like this one, ultimately published in the Journal of Addiction Medicine, that tested impairment acutely (0-6 hours after use), residually (7 hours to 20 days after use), and long term (3 weeks or longer) after use.1 Though your area may have legal protections for “off-duty” marijuana use, there can still be risk to on-the-job work due to effects like these.1
Workplace safety policies exist to prevent injuries before they happen. Removing marijuana from testing programs entirely can increase risk, especially in environments where impairment could lead to serious harm. Researchers and workplace safety analysts have pointed out that impairment due to substances can contribute to workplace accidents, and employers need tools to identify potential risks.
While many states have legalized marijuana in some form, marijuana remains illegal under federal law as of this writing. Employers with federal contracts, regulated positions, or safety-sensitive operations may still be required to test for marijuana under federal drug-free workplace standards. Even for employers not directly regulated at the federal level, drug-free workplace policies help protect businesses from liability and demonstrate a commitment to employee safety and professionalism.
Training supervisors to recognize signs of impairment is essential. Observable behaviors such as slowed reactions, impaired coordination, or poor decision-making can support reasonable suspicion testing when safety may be at risk.
Policies should also reflect job roles. Safety-sensitive positions may require stricter testing protocols, while lower-risk roles may rely more on post-incident or reasonable suspicion testing.
Finally, employers should stay informed about state, city, and regional laws affecting marijuana testing and employment decisions. A list of current state overviews can be found here, but those can and do change regularly. Also, some cities and regions/counties may have their own laws. Policies should be reviewed regularly with your legal team to ensure compliance with all area requirements, especially if you have employees across multiple states or regions.
As a reminder, the goal is not punishment. It is prevention. A clear, well-communicated drug testing policy that includes marijuana helps protect employees, reduce risk, and supports a safe and productive workplace.
Citations
- Crean, R. D., Crane, N. A., & Mason, B. J. (2011). An evidence based review of acute and long-term effects of cannabis use on executive cognitive functions. Journal of addiction medicine, 5(1), 1–8. https://doi.org/10.1097/ADM.0b013e31820c23fa
Sources:
Clearing the Haze: Exploring the Movement Away from Marijuana Testing. (2024, March 29). JD Supra. https://www.jdsupra.com/legalnews/clearing-the-haze-exploring-the-7842850/
Crean, R. D., Crane, N. A., & Mason, B. J. (2011). An evidence based review of acute and long-term effects of cannabis use on executive cognitive functions. Journal of addiction medicine, 5(1), 1–8. https://doi.org/10.1097/ADM.0b013e31820c23fa
Diem, N. (2025, November 12). Clearing the Haze: Exploring the Movement Away from Marijuana Testing | Mitratech. Mitratech. https://mitratech.com/resource-hub/blog/clearing-the-haze-exploring-the-movement-away-from-marijuana-testing/
Institute for Behavior and Health, Inc. (2015, March). Institute for Behavior and Health, Inc. 6191 Executive Boulevard Rockville, Maryland. https://www.dfaf.org/wp-content/uploads/2018/08/Workplace-Drug-Testing-IBH.pdf