Fermilab is a federal site, and while marijuana has been legalized in Illinois, it remains a controlled substance under federal law and is therefore prohibited on Fermilab property. Marijuana (and other controlled substances) prescribed for or administered to the employee by a licensed physician are also prohibited on Fermilab property. This prohibition applies to all areas of the Fermilab site, including the public areas and the Village.

From American Institute of Physics’ FYI, Dec. 20, 2016: The COMPETES law has been used to set policy for the National Science Foundation, the National Institute of Standards and Technology, the Office of Science and Technology Policy, the Department of Energy Office of Science and various STEM education programs across the federal government.