The dispensary calls the doctor and verifies that you are his patient. Then you verify that you are you. Some places have their own cards- which don't got on your CDL and are good for that place only. Each place it's a bit different. Just make a copy of your letter, have CA ID and keep it all in your wallet. Friend of mine made a half sized copy- just barely readable. (Purses are so nice- no space problems!) - Granny:hippy: