Do you think this is wrongful termination?

I work at a restaurant. My friend got in trouble for going out to her car to smoke a cigarette, since we are no longer allowed to do it on the back dock. It's a fenced-in area behind the restaurant where the dumpsters, cleaning products, etc. are kept. One of our district managers saw her smoking and he wants her to be fired. Does anyone know if this is illegal? Another friend said that since she wasn't doing it in the restaurant, it's a violation of her civil liberties to keep her from smoking in her own car. We aren't allowed any kind of break, even if we work all day or night. If we had a break, we wouldn't have to sneak out to our cars in the first place! Plus, our in-house managers smoke on the back dock or in their cars, but still expect us not to! So, is this something she could fight? Could it be considered wrongful termination?