Arizona Alcohol Laws

My two sisters and I will go out on weekends. I do not know if anyone is aware of the laws in Arizona, but I have a question. Two of us are over 21 years, but my little sister is only 19. It will be our designated driver. Are the bars / clubs to let them in, so she will not drop us off and then back? I thought they were so long she was not sitting at the bar ... but I'm not sure. If you do not know the laws here, I wonder if there is somewhere I can read it. Thank you very much.

No, they will not leave it in a real club, unless they do not check IDs. Your best bet is to go to a restaurant / bar (mostly sushi and Mexico) where you can spend time but they do ID if you buy a drink.