Massachusetts’ highest court last month became the first nationally to rule that many job applicants and employees who are medically certified to use marijuana cannot be automatically denied employment if they test positive for the drug.

Massachusetts is one of many states – now more than half – with statutes permitting marijuana use for medicinal purposes. Those state laws protect users from criminal prosecution, but the large majority of the statutes (including in Massachusetts) are silent on whether employers are free to deny employment to those who test positive for “medical marijuana.” Until now, every court to rule on the issue had held that employers may refuse to hire those individuals based simply on a positive test.

With this ruling, employers in the Bay State must revamp their thinking and possibly even hire or retain known medical marijuana users.

In Barbuto v. Advantage Sales and Marketing, LLC, the plaintiff was hired into a marketing position, then discharged after one day because her drug test came back positive for marijuana. The plaintiff previously had told her supervisor that she would test positive because she had been medically certified to use marijuana for relief from her gastrointestinal disorder. She used marijuana at her home in the evening, two or three times weekly.

Marijuana use of any kind – medicinal or recreational – is illegal under the federal Controlled Substances Act. The employer in Barbuto terminated the plaintiff on that basis. The trial court adopted the employer’s position and immediately dismissed the plaintiff’s claim.

On appeal, the Massachusetts Supreme Judicial Court classified the plaintiff’s gastrointestinal disorder as a “handicap” under the state’s anti-discrimination statute and analyzed the claim as a court would any other disability discrimination case. In other words, the high court concluded that the lower court should have heard evidence on whether the employer could have reasonably accommodated the plaintiff’s use of medical marijuana without the employer suffering an undue hardship. The high court also held that the employer had an obligation to consider the proposed accommodation by engaging the plaintiff in an interactive process.

In that process, employers in Massachusetts now must “determine whether there were equally effective medical alternatives to the prescribed medication whose use would not be in violation of [the employers’ drug-free workplace] policy.” That could prove daunting for employers whose managers and human resources professionals do not moonlight as practicing physicians. Popping two aspirin probably is not an option.

If there is no “effective medical alternative,” the employer must prove that employing a medical marijuana user would cause an undue hardship.

The employer in Barbuto asserted that accommodating marijuana use is per se unreasonable because the drug is illegal under federal law. Other courts, including those in New Mexico (in 2016) and Oregon (in 2010), have emphasized federal illegality in holding that employers may refuse to hire medical marijuana users under any circumstances.

The Massachusetts high court was not impressed, reasoning that only the employee, not the employer, is susceptible to federal criminal prosecution, and noting that because so many state legislatures have recognized the benefits of medical marijuana, it would not be “respectful” to Massachusetts voters to label the drug as per se unreasonable.

This is not to say that Massachusetts employers never can reject the employment of medical marijuana users. It depends on the circumstances. For example, the court held that an undue hardship would exist if the employer can demonstrate that continued use of marijuana would impair the employee’s work, or would pose an “unacceptably significant” safety risk. In addition, employees subject to the U.S. Department of Transportation regulations, as well as certain employees of federal government contractors obligated to comply with the Drug Free Workplace Act, are prohibited from employment should they use marijuana.

And, of course, medical marijuana users never may use the drug at work or be under the influence while working.

The legal battle may not be over in Massachusetts. The Barbuto court remarked that the employer had waived an argument that federal “preemption” had required the court to conclude that federal illegality of marijuana trumped any analysis under the Massachusetts anti-discrimination and medical marijuana statutes. “Preemption” is a nuanced legal argument embraced by other courts in this context, including those in New Mexico and Oregon. Could a Massachusetts federal court do likewise if confronted with the issue? Perhaps.