Federal employees were told this week that marijuana continues to be illegal for them, even though medical and recreational use of the drug is now legal in a growing number of states.

In a memo, Director of the Office of Personnel Management Katherine Archuleta told federal employees, “Federal law on marijuana remains unchanged. Marijuana is categorized as a controlled substance under Schedule I of the Controlled Substance Act. Thus knowing or intentional marijuana possession is illegal, even if an individual has no intent to manufacture, distribute, or dispense marijuana.”

Archuleta noted several states and Washington, D.C. have decriminalized the use of marijuana. In addition, Washington, D.C. and 23 states have authorized adult use of medical marijuana, and four states have legalized recreational marijuana for adults. “These changes to state law have raised questions about whether Federal employees in these jurisdictions may use marijuana as provided for in state law,” she wrote.

Adults 21 and older in Washington, D.C. are allowed to possess up to 2 ounces of marijuana. It is still prohibited on federally administered properties such as the National Mall.

There are about 4.1 million federal employees and military personnel in the United States, according to The Washington Post.

Archuleta noted marijuana use can be a basis for firing in some situations. She added the federal government offers prevention, treatment and rehabilitation programs for civilian employees with drug problems.

Many government agencies do not give employees regular drug tests, the article notes. Employees who undergo random and routine drug testing by federal agencies generally have jobs related to national security and law enforcement. Supervisors may call for drug testing when they have reasonable suspicion an employee is using drugs at work.