Most commonly prescribed for migraines, the recent legalization of medical marijuana and recreational marijuana is giving many employers a headache of their own. Technically, drug use (whether illicit or medicinal) is still illegal on the federal level, although it appears the government has no plan to interfere. Consequently, employers have been forced to buckle down and figure it out for themselves.

Last November, Colorado became one of the first states to legalize marijuana for recreational use, further befuddling employers in a world of legislature that was already as unclear as it was controversial. According to Colorado’s medical use clause, the Amendment “was not intended to create an unfettered right to medical use of marijuana” or “to violate employer’s policies and practices regarding use of controlled substances.” Or, in English, doesn’t stop employers from upholding a zero-tolerance policy on drugs in the workplace. Sounds straightforward, but it hasn’t deterred lawsuits from disgruntled employees who felt as though they were inappropriately terminated.

So what are the accepted exceptions for marijuana in a “drug-free” workplace? According to the Department of Transportation, there aren’t any. Despite the changes on Capitol Hill, marijuana’s high risk for abuse and lack of accepted medical use keep it a Schedule I drug in the Controlled Substances Act. The DOT recently issued a press release stating “[Marijuana] remains unacceptable for any safety‐sensitive employee subject to drug testing under the Department of Transportation’s drug testing regulations to use marijuana.”

Still, eliminating drugs in the workplace remains a difficult task for the number one attractant of drug users: small business. The Occupational Safety and Health Administration attributes this to too few regulations outside of D.O.T. mandates, unwillingness to confront the issue, and reluctance to submit employees to drug testing.

So what should employers do? Well, since there is no recourse for legal action after an employee is wrongly fired for testing positive for drugs, it is essential that small businesses draft clear, concise, zero-tolerance drug policies. Employees must be made aware of the policy and acknowledge it in writing. Lastly, some form of regular, consistent employee drug testing should be stated in the policy for best practice and reinforcement.

The 2010 National Study on Drug Use and Health reported “marijuana accounted for 4.5 million of the estimated 7.1 million Americans dependent on or abusing illicit drugs.” And the numbers are growing. Marijuana’s active ingredient, tetrahydrocannabinol (or THC), is a psychoactive addict inhibitor. Today’s marijuana isn’t what it used to be. Recent studies show THC potency levels to be anywhere from 12-30%. By comparison, the potency of marijuana in the 1970s averaged just below 4%.