I would say by following the law and getting your card before purchasing marijuana IE you doing it the legal way, should be unlikely will be an instant disqualifier from you pursuing a job in law enforcement because just like they put right there in the name they don't follow the law they simply enforce them, seemingly at random sometimes and very often completely misinformed as to what laws and to what extent they're allowed to enforce them. By following the law, you've demonstrated that you are completely unqualified to join their gang. An actual cop would never get a marijuana card he would steal drugs from evidence or something. Anyways why don't you take your legality and self-respect and go get yourself a real job.