I don't see anything about a card being legal tender listed there. Its far safer to have the doctors signed MMJ authorization form. And anything can easily be forged in this day and age. Like I said I could easily forge a MJ card here at home in 15 minutes and laminate it. I realize the cards are more convienient to carry than a folded up copy of an MMJ authorization but I try to stay as legal as I can considering the vague laws.