November 8, 2023

As states enact new marijuana laws, employers should respond by updating their policies, handbooks and drug testing procedures, while also ensuring employees and managers are trained on how to recognize and report signs of impairment. 

While marijuana continues to be illegal under federal law, state laws vary considerably. Recreational use of marijuana is legalized in 24 states, while 38 states have legalized it for medical purposes. In October, California passed a law barring state employers from discriminating against applicants and employees based on their off the job use of cannabis unless they seek or hold an exempted role. The law also makes it illegal to discriminate against applicants and employees on the basis of drug tests that simply detect “nonpsychoactive cannabis metabolites.” The California law goes into effect on January 1, 2024. 

Balancing Worker Rights and Safety 

Although workers in states where cannabis is legal have the freedom to use marijuana during their off-duty hours, they aren’t exempt from workplace safety regulations. Being under the influence of marijuana at work can jeopardize the safety of a workforce. Research by the National Institute on Drug Abuse found that employees who tested positive for marijuana experienced 55% more industrial accidents, 85% more injuries, and 75% more absenteeism compared to those who tested negative. 

Regardless of jurisdiction, employers should have clear policies advising employees that cannabis use during work hours—including meal breaks and rest breaks—is not permitted, and that cannabis use is not permitted on company premises, including in an employee’s car in the company parking lot. 

Proving Impairment in the Workplace 

Unlike alcohol, where a simple breathalyzer test can determine impairment, marijuana’s effects on an individual can vary greatly depending on factors such as consumption method, marijuana strain and tolerance.  

Studies have shown that THC – the psychoactive compound that gives cannabis users a high – lingers in the body as nonpsychoactive metabolites long after the impairment has disappeared. As a result, many states have laws requiring employers to prove impairment rather than just the presence of THC.  

Chemical drug tests such as urinalysis, oral fluid and hair are only indicative of prior use, not active THC impairment. In contrast, saliva/oral fluids and blood tests provide the best measure of active THC and impairment. 

Training to Recognize Impaired Behavior 

Even if marijuana testing isn’t permitted in a state, employers should ensure employees, supervisors and managers have been trained to recognize impaired behaviors to prevent accidents before they occur. The most common signs of marijuana use include red eyes, the unmistakable aroma on clothing, slow response times, poor coordination, lethargy and increased appetite. Other symptoms include panic, paranoia, anxiety and hallucinations. 

By focusing on behavior and performance rather than the mere presence of drugs, businesses can maintain safe work environments and stay legal. 

For employee and manager safety training on how to recognize and prevent drugs and alcohol in the workplace, click here.  



Andrea Foster-Mack