A medical marijuana certification letter is issued by a state approved licensed practitioner that indicates you have a qualifying condition that allows you to obtain medical marijuana. A medical marijuana card is issued by the Department of Pharmacy. It is a personal identification card that shows you are a legal Virginia resident registered with the Virginia Department of Pharmacy allowing you to legally buy, possess, and consume medical marijuana. The certification letter is required for the Department of Pharmacy to issue a medical marijuana card which is valid for one year.