Colorado's Supreme Court says attorneys in the state can advise marijuana businesses on how to navigate the industry's legal complexities without fear of violating state ethics rules.

The court issued its rule change Monday. It offers attorneys assurance that they won't be punished solely for giving clients pot-related legal advice, as long as they believe those clients are operating legally. Attorneys are also required to advise clients about federal law and policy.

Colorado legalized recreational sales of the drug in January, but they remain illegal under federal law.

The court's attorney regulation counsel, James Coyle, says no lawyer has ever been sanctioned solely for giving legal advice, but concern about committing ethics violations remained. He says the rule change gives attorneys new guidance.