Study: After-Hours Marijuana Use Doesn’t Negatively Impact Job Performance


Cannabis consumption while away from the job is not associated with any lingering adverse effects on workplace performance, according to data published in the journal Group & Organization Management.

A pair of researchers from San Diego State University and Auburn University in Alabama compiled data from 281 employees and their direct supervisors with respect to marijuana use and job performance. Authors reported that an employee’s cannabis use either immediately before or during work hours was associated with “counterproductive work behaviors,” whereas “after-work cannabis use was not related (positively or negatively) to any form of performance as rated by the user’s direct supervisor.”

Authors concluded, “[C]ontrary to commonly held assumptions, not all forms of cannabis use harmed performance. In fact, after-work cannabis use did not relate to any of the workplace performance dimensions. This finding casts doubt on some stereotypes of cannabis users and suggests a need for further methodological and theoretical development in the field of substance use.”

Commenting on the study’s findings, NORML’s Deputy Director Paul Armentano said: “Suspicionless marijuana testing never has been an evidence-based policy. Rather, these discriminatory practices are a holdover from the zeitgeist of the 1980s ‘war on drugs.’ But times have changed; attitudes have changed, and in many places, the marijuana laws have changed. It is time for workplace policies to adapt to this new reality.”

The study’s authors acknowledged that despite the widespread implementation of workplace drug screening programs, “there is virtually no empirical research exploring cannabis use in relation to the modern workplace.”

The findings of the study are similar to those of a recent literature review published in the journal Substance Use and Misuse which concluded, “[T]he current body of evidence does not provide sufficient evidence to support the position that cannabis users are at increased risk of occupational injury.” A prior literature review, published in 2017 by the US National Academies of Sciences, Engineering, and Medicine also concluded, “There is no or insufficient evidence to support … a statistical association between cannabis use and … occupational accidents or injuries.”

In recent months, lawmakers in several municipalities – including New York City, Richmond, Virginia, and Washington, DC – have enacted legislation limiting the use of marijuana-specific pre-employment drug screening.

Both Maine and Nevada have enacted state-specific legislation barring certain employers from refusing to hire a worker solely because he or she tested positive for cannabis on a pre-employment drug screen.

The full text of the study, “Altered states or much to do about nothing? A study of when cannabis is used in relation to the impact it has on performance,” is available online here. Additional information is available from the NORML fact-sheet, “Marijuana Legalization and Impact on the Workplace.”

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