There is something I don’t quite understand? If a person is allowed to have medical marijuana then it isn’t illegal correct? It is a controlled substance no different than if one is prescribed Tylenol #3 for a toothache or a muscle relaxer for a back condition. So... will ATF deny anyone the right to bear arms if they had been/are currently on any controlled pharmaceutical drug?
It's still illegal. State law is trumped by Federal law:
This Constitution, and the Laws of the United States which shall be made in pursuance thereof; and all treaties made, or which shall be made, under the authority of the United States, shall be the supreme law of the land; and the judges in every state shall be bound thereby, anything in the constitution or laws of any state to the contrary notwithstanding.
The SCOTUS upheld Federal control of drugs, even if it is not interstate commerce, just a few years ago:
That is why some goverors, such as Brewer and Christie, have been hesitant to implement their states' med. marijuana laws. All participants, including doctors, state officials, and end-users, and violating federal law and subject to prosecution.