The recent passage of marijuana-use legislation in states around the country raises new issues for employees and employers alike. Twenty-three states and the District of Columbia permit some form of "legalized" marijuana. Eight of these states have specifically addressed marijuana in the workplace by passing antidiscrimination laws (Arizona, Connecticut, Delaware, Illinois, Maine, Minnesota, Nevada and New York). While the regulations of each state that has passed antidiscrimination laws are slightly different, they have one element in common: an employer may not take an adverse action merely because an employee is registered in the state's medical marijuana program.

What is also common is that an employer does not have to tolerate use, possession or impairment on the premises or during working hours. Where the states with antidiscrimination laws begin to diverge is on the topic of "off-duty" lawful use of medical marijuana. Arizona, Delaware and Minnesota have specifically addressed medical marijuana in the context of drug testing. For example, while Minnesota allows an employer to discipline an employee for being impaired at work, it also provides that an employer may not take an adverse action against an employee for a positive drug test (for medical cannabis) if that employee proves that he or she is a lawfully registered patient in the state's program.

Federal law complicates the analysis, as marijuana is still an illegal substance, and federal law does not recognize a lawful medical-use exception. Moreover, federal law mandates, in certain circumstances, strict compliance with zero-tolerance policies in the workplace (for example, for certain safety-sensitive positions and federal contractors). In states lacking medical marijuana antidiscrimination laws, employees have attempted to challenge their employers' adverse decisions by asserting that marijuana use while off duty is protected under their states' general lawful consumable use statutes. These statutes provide that employers may not take adverse actions against employees for use or enjoyment of lawful consumable products off duty and off premises. Colorado has recently rejected this argument in Coats v. Dish Network, stating that in order for the lawful consumable use statute to protect an employee's conduct, the conduct must be lawful under both state and federal law.

The patchwork of often-conflicting state laws on "legal" marijuana use creates challenges, particularly for employers with operations in multiple states, but also for employers operating in only one locale that has enacted marijuana-use legislation.