How Does Marijuana Impairment Impact Workplace Testing Programs?


How Does Marijuana Impairment Impact Workplace Testing Programs?

By Sharon Bottcher at Current Consulting Group (CCG)

This information is provided for educational purposes only. Reader retains full responsibility for the use of the information contained herein. 

The Controlled Substances Act of the U.S. Drug Enforcement Administration currently classifies marijuana as a Schedule I substance, meaning that it has no accepted medical use and has a high potential for abuse. Due of the status of Schedule I drugs, research is almost impossible, as most research institutes are banned from holding these substances. Therefore, access to study marijuana for its potential medicinal value and the health and safety effects is limited at this time. Also, according to the U.S. Centers for Disease Control and Prevention, marijuana — or cannabis — is the most commonly-used federally illegal drug in the United States.[1]

Regardless of the federal prohibition of marijuana, the growing acceptance of marijuana use in recent years has led to the explosion of state laws legalizing the use of marijuana for medical and recreational use. Currently twenty-three states as well as Washington D.C., have passed laws legalizing marijuana for non-medical adult use and forty-one states and Washington, D.C., for medicinal purposes.

Early in the legalization of marijuana most states provided few or no job protection for off-duty use. Newer laws tend to afford more job protection and employers must know the ins and outs of the law for compliance. In some states, laws protect medical marijuana users but not recreational users while others state laws provide employment protections for both. As part of the employee protections, many states passing medicinal and recreational marijuana laws have put into place stipulations that require employers to prove there is a connection between a positive drug test result and actual impairment before taking adverse employment action.

What Determines Impairment?

If state laws protect employees and limits employers from employee discipline based solely on a positive marijuana test, how are employers able to protect their employees from an individual under the influence or impaired by marijuana during work hours?

For starters, in states that require impairment as part of the testing process, employers must first understand that marijuana impairment refers to the effects of cannabis on cognition, motor skills, perception, and physical health. Current testing methods do not identify impairment or intoxication, only the presence of marijuana metabolites or THC, the psychoactive ingredient in marijuana.

There is no clear definition or measurement of marijuana impairment and employers must establish a reasonable belief that individual work abilities are impaired by marijuana. Therefore, the safest and most comprehensive way to determine impairment is to balance recent-use drug testing with an investigation into whether an employee exhibited any of the physical and/or behavioral signs typically associated with impairment.

To successfully prove impairment, the employer must first gather sufficient evidence or traits that would justify and merit the request for a drug test. There is not an all-inclusive list of signs and symptoms of impairment; however, there are common signs and symptoms of possible impairment to watch for which include, but are not limited to the following:

  • Physical: poor appearance/hygiene, sweating, tremors, restlessness, bloodshot eyes, dilated or constricted pupils, smell or odor of marijuana, etc.
  • Psychosocial: mood fluctuations, inappropriate verbal or emotional responses, irritability, confusion, memory lapses, isolation, lack of focus, lying, etc.
  • Performance: calling in sick frequently or working more overtime, arriving late/leaving early, extended breaks, errors in judgment, deterioration in performance, non-compliance with policies, changes in quality of work, etc.

The identified behaviors should be properly documented, as they serve as a record for witnessed impairment behaviors. The drug test is then used to rule out prohibited drugs as a source of a particular behavior. Documenting signs and symptoms of impairment does not necessarily mean that an individual is using drugs and needs a drug test. Rather, a drug test for post-documented signs is used to exclude possible impairment as a cause of unusual behavior.

The next step is the most difficult and many managers fear confronting individuals with the witnessed behavior, but proper documentation and training will help alleviate concerns with addressing employees exhibiting signs of impairment.

Developing a Workplace Policy on Drug Impairment 

It is vital to include specific state law requirements in your policy. At a minimum, your policy should include the impact of possible impairment, company or state definitions of “impairment” or “under the influence,” and required employee conduct. The policy should also clearly indicate the employer’s position on the use, possession, or being under the influence of substances while at work.

While the employer is ultimately responsible for developing a policy that includes the applicable provisions required, the supervisor has a vital role to play in the safety of their teams. Supervisors should be educated regularly on policy changes as regular reviews and updates occur. The success of the supervisor, in part, is determined by an accurate and comprehensive policy.


Keeping up with the influx of marijuana laws is a grueling task but we can make it easy for you. If you need a compliant policy or if you’re interested in learning more about our training services, contact the experts at Current Consulting Group at 954.944.0400 or [email protected].

End Note

[1] “Data and Statistics.” Centers for Disease Control and Prevention, 8 June 2021,

© 2010-2023 The Current Consulting Group, LLC – No portion of this article may be reproduced, retransmitted, posted on a website, or used in any manner without the written consent of the Current Consulting Group, LLC. When permission is granted to reproduce this article in any way, full attribution to the author and copyright holder is required.


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