G/F fired from bar....legality question

[Histrionic]

So my g/f started a job at a nice bar in the local area and had been working there for about five days. Today she came home and announced that she had been fired. When I asked her the reason she stated the manager had brought her into the office and said he liked her, she had done a great job thus far, but she thought she had a drinking problem.

At this bar she was told by this manager right when she started that she could do one shot per hour when she worked, as could all of the other bartenders/waitresses (this is a really cool laid back bar in a nice area). She would take shots with the other employees (and managers) when they did, but never without. She also never showed up to work drunk or even tipsy. Truth be told she really dosen't even drink that often. I'm actually thinking because of all this that they just gave her that as a bogus reasoning when it was really something else. However, if EVERY shot she did at the bar while at work was approved by a manager (which it was) and she never came to the job having already previously been drinking, isnt't this grounds for a lawsuit? Isn't this is a personal issue that they cant fire someone for anyway?