Early this year, a disabled former automobile body worker named Greg Vialpando explained to lawmakers in New Mexico how medical marijuana helped his chronic back pain.
State legislators were considering a bill backed by workers’ compensation insurers that would have exempted them from paying for medical marijuana. But Mr. Vialpando and another patient described how smoking the drug let them escape years of stupor caused by powerful prescription narcotic drugs known as opioids.
The lawmakers ended up dropping the bill, and Mr. Vialpando’s expenses for buying marijuana are covered by insurance.
“I would recommend that people use medical marijuana over opioids any day,” Mr. Vialpando, 58, said in a telephone interview.
For businesses and insurers, a string of ballot victories this month for marijuana advocates are adding to an intensifying conundrum about the drug and issues such as insurance coverage, employee drug testing and workplace safety.
Voters in California, Massachusetts, Maine and Nevada approved initiatives legalizing the recreational use of marijuana, while voters in Arkansas, Florida, Montana and North Dakota passed proposals for its medical use. In total, 28 states now permit or will soon permit medical use of marijuana while eight states have approved recreational use.
“We are entering this conflict between a social policy decision and a workplace that is highly regulated,” said Alex Swedlow, the chief executive of the California Workers’ Compensation Institute, a research organization.
A major part of the predicament centers on unclear science about the benefits of marijuana or the dozens of compounds, known as cannabinoids, that are found in the plant.
For its part, the Food and Drug Administration has approved only a synthetic version of a cannabinoid and a similar drug for narrow uses, such as to treat nausea in chemotherapy patients or to stimulate the appetites of patients with AIDS. Typically, health insurers will pay for marijuana-related drugs only for F.D.A.-approved uses.
But state medical marijuana laws usually give doctors permission to recommend marijuana to a patient with a “debilitating” condition, a phrase that can encompass problems including glaucoma, cancer and chronic pain.
Usually, patients pay for the drug themselves and several states have explicitly exempted workplace compensation insurers for covering such costs.
But as a result of recent state court rulings in New Mexico, workplace insurers there are required to pay for marijuana-based treatments if they are recommended by a doctor. And lower courts in Connecticut, Maine, Massachusetts and Michigan have issued rulings directing workplace insurers to do so.
The number of patients receiving such coverage is small. And because marijuana is illegal under federal law, insurers paying for the drug must use a financial workaround to avoid violations. One strategy is to reimburse patients for their costs rather than make a direct payment to a marijuana dispensary.
“The legality of this has not been tested in court,” said Ellen Sims Langille, the general counsel of the California Workers’ Compensation Institute.
State marijuana laws vary. But broadly speaking, in states that have legalized marijuana for recreational use, it is not a crime for residents to possess small quantities of the drug and it is legal for licensed dispensaries to sell it. Patients approved to use the drug and dispensaries enjoy similar protections in states with medical marijuana laws.
However, all states have retained laws that protect the right of employers to have a drug-free workplace. An employer can withdraw a job offer to a candidate who tests positive for marijuana on a pre-employment drug screening or fire an employee who tests positive.