as far as cards go.. the only people who check your age are the people who issue the card. the card will work fine almost everywhere in northern cali, however, in southern cali, you need to carry the actual doctor's note with you. the card is not enuff. for example, at the dispensery i work at, we cannot let you in without a doctor's note (even if you have a med can card or a card from another club). the reason for this is that in los angeles county, cops dont care about cards, they need to see a doctor's note (prescription).

p.s.
there are about 15 clubs in la that i know of..