In the private sector, at least, companies that are inclined to do so could simply change their drug testing policies, but those that receive federal contracts are required to prohibit the use of marijuana as a condition of participation under the Drug-Free Workplace Act of 1988.



The federalDepartment of Transportation also issued new guidelineslast year that prohibit the use of medical marijuana for transportation workers in safety-sensitive jobs including pilots, school bus drivers, truck drivers, subway operators, ship captains, and transit fire-armed security, even in states where it is legal.



And employers in all sectors have a “general duty” to provide a safe work environment under the Occupational Safety and Health Administration, OSHA, which some suggest is reason enough to terminate workers who test positive for THC.



Then, of course, there’s liability to consider.



Say an employee comes to work under the influence (of any substance) and gets into a car accident or makes a critical mistake with a customer. It’s the employer who gets sued.



"It really boils down to this: An employer's right to maintain a drug-free workplace is critical," says Denise Davis, a spokeswoman for the California Chamber of Commerce. "It protects the safety of all workers and limits exposure to potentially costly litigation."



The Law: A Moving Target

The landmark 2008 Supreme Court ruling in California, involving a systems administrator who was fired by Sacramento-based RagingWire Telecommunication(now known as RagingWire Enterprise Soutions) for using medical marijuana, offers the most definitive guidance for employers thus far.



The court ruled that drug testing in the state was legal, that firing an employee for use of medical marijuana was not tantamount to discrimination and that employers are not obligated to accommodate the use of medical marijuana—even outside the workplace.



In other words, while the state’s medical marijuana laws protect patients from criminal prosecution, it provides no protection on the job.



After all, pot remains classified as an illegal substance under federal law.



“The California Supreme Court gave carte blanche for employers to discriminate against medical marijuana patients,” says Joe Elford, legal counsel for Americans for Safe Access, a medical marijuana advocacy group.



But the door remains open for less rigid interpretation.



At present, seven medical marijuana states have implicit employee protections in place, where the law mentions only on-the-job consumption or impairment as grounds for termination—Colorado, Hawaii, Michigan, Montana, New Jersey, New Mexico and Vermont.



Two others, Rhode Island and Maine, have explicit protections for medical marijuana patients written into their legislation.



For example, the 2006 legislative bill that legalized the use of medical marijuana in Rhode Island states that “no school, employer or landlord may refuse to enroll, employ or lease to or otherwise penalize a person solely for his or her status as a card holder” (of medical marijuana).



Thus far, however, none have been tested in court.



