The news last November he'd been terminated was devastating for Casias, 29, who took great pride in his job, once earning the honor of Associate of the Year.
"It hurts. It hurts because I care. I care a lot about the store. I always wanted to make sure I do well," he told ABC News.
Casias started taking the medicine last June to cope with pain from sinus cancer and a brain tumor. He says the rare form of cancer causes him pain constantly and he almost died when he was first diagnosed.
Casias sprained his knee at work last November and underwent the routine drug test that follows all workplace injuries. Questioned about his positive test, Casias told management about his condition and presented a state card authorizing his marijuana use for medical purposes, but he was fired anyway. Casias says management told him Walmart does not honor medical marijuana cards.
"I just can't believe that it has to be this way. I don't see why they have to fire me," he said.
Michigan is one of 14 states where medical marijuana is legal, but employers in the Wolverine state can and do terminate employees who fail drug tests. Walmart policy, like the policy of other companies, indicates that in states such as Michigan which allow marijuana use for medical purposes, the store can still terminate an employee following a positive drug test. The law in Michigan says employers do not have to accommodate the ingestion of marijuana in the workplace or employees working while under the influence.
Casias has been receiving Michigan unemployment compensation since his termination and was notified that the company would challenge his eligibility for benefits during a phone hearing on March 31. A Walmart spokesman says that's not the case -- it won't challenge Casias' eligibility.
Even still, Casias thinks he may be entitled to compensation because he did not break any Michigan laws by using marijuana for pain. "I'm currently taking a look at all my options available," he said. "I am currently talking to an attorney at this point."
"This is just an unfortunate situation all around," Walmart spokesman Greg Rossiter told ABC News. "We're sympathetic to Mr. Casias' condition, but like other companies we have to consider the overall safety of our customers and our associates, including Mr. Casias when making a difficult decision like this."
Medical Marijuana Hazardous in Workplace?
Certainly using a mind-altering drug on the job is something that would trouble any employer, but Casias says he never used the marijuana before or during work. He was in severe pain regularly so it would make sense that the drug was detected given that it can take weeks for marijuana to leave the system.
Doctors say a number of medicines or combination of medicines, such as antihistamines, could pose a danger at the workplace. And medical marijuana, which is thought to be relatively safe, falls into the category of substances that could be hazardous to the workplace. Casias unloaded trucks for Walmart.
"I'd be concerned from an occupational hazard standpoint," said Dr. Martin Makary, associate professor of Health Policy at Johns Hopkins University. "I think this individual could drop or mishandle or lose control of the box because of their impaired mind-altered judgment. The job would really need to require no judgment of any kind. No coordination, no technical judgment or no thinking skills in order to argue it would be safe in the workplace."
On the other hand, Makary says that if a person used medical marijuana or Cannabis on a Friday night and went to work on Sunday, they wouldn't be impaired on the job.
Would the situation have turned out differently if Casias had told Walmart about his treatment? Casias says he thought the treatment was between him and his doctor. And why didn't Walmart use its discretion to take into account the fact that someone who apparently was a pretty good worker, earning the honor of Associate of the Year in 2008, was taking the marijuana for medicinal purposes? The company, after all, did not point out any issues with his performance at the time of his termination.
Michigan attorney Michael Komorn, who has represented several clients in medical marijuana cases and does for the Michigan Medical Marijuana Association, says that Walmart made a specific choice to single out Casias for exercising his free will in compliance with the law.
Walmart Firing 'Uncompassionate'
"It's offensive. It's uncompassionate. The guy's got cancer and you fire him."
While Michigan law protects any employer's right to terminate for marijuana use, the law also states that a qualifying patient who has been issued and possesses a registry identification card shall not be subject to penalty in any manner, or denied any right or privilege or disciplinary action by a business for medical marijuana use.
Komorn believes citizens who use medical marijuana in Michigan and elsewhere encounter all kinds problems with law enforcement and mainstream society because of the stigma that society places on marijuana use.
"Walmart, this great outlet, has embraced the stigma of marijuana," he said. "There's a transition phase that we're going through that involves people adjusting their view and reaction to marijuana."
Komorn says the Michigan statute covering medical marijuana is written in such a way that there is conflict. An employer may have existing contracts that say it can terminate the employee for marijuana use. In a landlord/tenant agreement, a landlord could say he doesn't allow marijuana on the premises. And, a patient who is operating a vehicle with marijuana in his system can still be convicted of driving under the influence.
Komorn hopes the conflicts will be resolved through litigation. "In order to protect patients there has to be an evolution in thinking," he said.