On Monday, the Colorado Supreme Court ruled 6-0 that businesses have the right to terminate employees for using marijuana, even if they are off-duty at the time, upholding two lower court decisions, The Wall Street Journal reports.

In their decision against a quadriplegic man fired for using medical marijuana at home to calm violent spasms, the court explained that while use of the drug may be lawful at a state level, marijuana possession remains a federal crime.

“The term ‘lawful’ refers only to those activities that are lawful under both state and federal law,” wrote the court. “Therefore, employees who engage in an activity such as medical marijuana use that is permitted by state law but unlawful under federal law are not protected by the statute.”

According to NBC News, Colorado follows California, Montana and Washington to become the fourth state to rule against workers fired for medical marijuana use.

“We are pleased the Colorado Supreme Court agreed with our position in this case,” Colorado Attorney General Cynthia H. Coffman said in a statement. “The court’s decision allows Colorado companies the freedom to write their own employment policies regarding marijuana.”

[Image via AP Images]