According to a DEA document (DEA-DCT-BUL-064-15), released under the Freedom of Information Act, they have encountered “medical marijuana” card holders acting as decoys for shipments of cannabis across the border.
According to the bulletin they have had instances of people crossing the border who smelled of Cannabis who claimed Medical Marijuana use. In the 2 instances cited the people had the smell of marijuana on them that have showed their state issued medical cannabis cards. In one instance they found a single gram which they confiscated, and in both instances they allowed the persons entry into the country without any charges.
What they fear, but have no documentation it has occurred, is that someone will keep the agents busy while a big load comes across the border. So as a warning to the agency they are expressing that this could be used as a tactic to bring cannabis into the country.
What a joke the document which was created in 2015 is.