Many employers choose to maintain a drug-free workplace in the interest of promoting employee safety, health and productivity. However, notwithstanding the fact that marijuana is prohibited under federal law, 33 states and Washington, D.C., now permit some form of marijuana use, and thus employers must consider whether a drug-free workplace policy contravenes any of these laws. This month's column offers some perspective on issues for employers to consider, including: background on what marijuana is; a summary of the legal landscape regarding whether and when an employer may engage in testing for marijuana use; and some suggestions concerning policies that employers may adopt to promote a drug-free workplace while respecting employees' new rights under medical or recreational marijuana laws.