Applied Evidence

Medical Cannabis: A guide to the clinical and legal landscapes

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Physician shield. Despite inconsistent and evolving state and federal laws, physicians are protected, based on the Conant v Walters decision, from prosecution or revocation of their prescriptive authority for the professional “recommendation” of the use of medical marijuana.19 In 2002, the US Ninth Circuit Court of Appeals upheld the permanent injunction, based on a physician’s First Amendment right to discuss medical marijuana with patients.


Mr. S is amenable to trial of Cannabis to relieve nausea and anorexia. He asks you if he is allowed to use Cannabis at work, were he to return to an office-based desk job—even part-time—during treatment for cancer.

How would you answer Mr. S? Patients are legally protected from workplace penalties and dismissal for using and consuming Cannabis in states with a medical Cannabis law (including the state in which Mr. S resides). However, all employers have some variability in corporate policy, especially if a person works in a federally supported or regulated occupation. It’s always helpful to advise patients who will be using medical Cannabis to be proactive and speak with a human resources or employee health department staff member before beginning a course of medical Cannabis. Additionally, Cannabis with any amount of THC has the ability to alter focus, concentration, and perceptions of time. Thus, if a patient using medical Cannabis with THC asks about driving to work, he should be given the same advice one would offer about driving after consuming alcohol or ingesting opioids.

Common concerns

Ignorance of legal status. Theoretically, the Conant v Walters decision protects physicians from investigation for recommending medical Cannabis even in states where it is illegal. However, you should adhere closely to procedures set out by your state. The National Council of State Legislatures provides up-to-date information on each state’s procedures and programs,18 and the American Society of Addiction Medicine ( has established standards of professionalism for physicians who discuss medical Cannabis with patients (TABLE).20

Table of Cannabis professionalism

Exposure to smoke. Cannabis smoke carries many of the same carcinogens found in tobacco smoke; furthermore, use of Cannabis and tobacco are highly correlated, confounding many population-based studies. The manner of inhalation of Cannabis can result in significantly higher levels of tar and carbon dioxide than with tobacco smoking. Because the effects of Cannabis last longer, however, people who smoke Cannabis may smoke it less often than tobacco smokers smoke tobacco.21

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