Workplace urine drug testing for an inactive THC metabolite is common in both federally regulated and non-regulated drug testing. A positive result does not document impairment, or even recent use, when impairment is likely the most important parameter being searched for by the drug testing procedure. Most cannabinoid testing does not detect imported synthetics. Currently, urine is the most widely tested matrix, but blood, plasma, oral fluid, and hair may also be accepted in federally regulated testing in the future. This article will discuss the history, the status quo, and the possible near term future of workplace testing for marijuana in employees.