Unfortunately not. The courts have ruled that even though you have a legal recommendation for cannabis, they can dictate the rules when you are working there. They can drug test you and if found positive and they have a zero tolerance policy, can legally dismiss you.
In one of the most publicized cases, the Colorado Supreme Court recently heard the case of Coats v. Dish Network, in which an employee of Dish Network sued under Colorado’s lawful off-duty activities law after being fired for failing a random drug test despite having a medical marijuana license. In a unanimous decision, the court found in favor of the company based on the fact that federal law still classifies marijuana as a controlled substance. Many in the medical marijuana community felt that the outcome of Coats highlights the need for further reforms concerning the use of medical marijuana and protections for those registered users.
Perry Solomon, MD