My friend used an employee bathroom and the cops both arrested us for Drunk In Public (DIP)? we're minority?

My friend used an employee bathroom of a liquor store and the manager called the Cops bec he failed to ask permission to use the bathroom (he flushed it! Didn’t make any mess). The cops came and qustion him (outside the store). As he was being questioned, I was inside the liquor store buying alcohol. I went outside to talk to both the cops and my friend to understand the situation. The cops told me to get a sober driver to pick both of us up bec. I told them that I had a few beers and that I was not the driver. So I called our driver, but she was BC bying more stuff for the party, then the cops both arrested us. The Cops didn't even give me a chance to call a cab or enough time to find her. I feel like I have a strong case bec. I can use the casher that sold the alcohol as my witness, the cops obviously doesn’t think that I'm intoxicated, endangering the public, or myself bec. one of them instructed me to find a driver, and the surveillance camera.