DANA POINT, Calif. — Supervisors should undergo reasonable suspicion training to enforce drug-free workplace policies and ensure worker safety, speakers said during the 2015 California Workers' Compensation & Risk Conference in Dana Point, California.

Employers' written substance abuse policies should state that the use, possession or sale of alcohol or illegal drugs isn't allowed on company property or during business hours, and that employees may not report to work while under the influence, Bernadette M. O'Brien, partner at Floyd, Skeren & Kelly L.L.P. in Sacramento, California, said Thursday during a session on the risks associated with legalized marijuana.

Employers should include that violating the policy can lead to disciplinary measures, such as termination, she added.

Ideally, two managers or supervisors per worksite should be trained on reasonable suspicion-based drug testing, Ms. O'Brien said. Noting that smell is a common red flag, she shared a recent example of a worker who returned from lunch smelling of alcohol and claiming it was from the gum he was chewing.

A worker who is under the influence of alcohol or drugs presents a safety hazard, speakers said.

Reasonable suspicion-based drug testing is a better option for employers than random drug testing, which isn't even permitted in California, Ms. O'Brien said, though there are exceptions for workers in some safety-sensitive jobs, such as Department of Transportation drivers.

And employers that do pre-employment drug testing should make sure applicants don't receive offer letters or start work until test results come back negative, she said, suggesting that employers also avoid emails that say, “Welcome to the job; we're so happy to have you; you're hired; and when can you start?”

Dealing with legalized medical marijuana is also proving to be challenging for workers compensation professionals, speakers said.

Despite being subjective, pain is a qualifying condition for medical marijuana in states like California and Colorado, said Mark Pew, senior vice president of product development at Prium, a Duluth, Georgia-based medical management company.

California lists “chronic pain” as one of more than 10 qualifying conditions for medical marijuana, Mr. Pew said, adding that other conditions include anorexia, cancer, migraines and seizures.

And Colorado considers “severe pain” a qualifying condition, he said, along with conditions like severe nausea and persistent muscle spasms.

In July, New Mexico became the first state to propose adding medical marijuana to its health care provider fee schedule, which would set the maximum payment that injured workers could be reimbursed for the drug, Mr. Pew said. In addition, the New Mexico Court of Appeals has ruled several times that medical marijuana should be classified as reasonable and necessary medical care for injured workers, he added.

Most of the evidence that points to the efficacy of medical marijuana is anecdotal at this point, Mr. Pew said. Even so, he says the treatment is “appropriate for some people in some circumstances with some conditions at some times.”

While it shouldn't be used as a first-line therapy, marijuana is safer than opioids, he said. He noted that you can't die directly from smoking marijuana, but that high doses of edibles which are absorbed through the digestive tract are dangerous, however.