Medical marijuana is now legal in 33 states, the District of Columbia and three United States territories, with more than 4 million Americans carrying medical cards for its use in treating conditions like chronic pain, arthritis, migraines, and cancer symptoms. But protections for employees who use cannabis under a doctor’s supervision differ widely by state. For instance, Oregon does not provide any protections for marijuana users, while Pennsylvania prohibits employers from discriminating or retaliating against employees based on their status as a medical marijuana patient, but do not require employers to make any accommodations for those employees. And while the federal Americans with Disabilities Act (ADA) require employers to provide reasonable accommodations to enable workers with disabilities to perform the essential functions of their jobs, it does not protect employees who use drugs that are illegal under the Controlled Substances Act, such as cannabis. It is best for employees who take marijuana for medical purposes to work with their doctors, their employer’s human resources department and an employment lawyer to know their rights.