If a bar serves alcohol to someone who is already apparently under the influence of alcohol, meaning they've consumed alcohol before they came to the bar or they've already consumed a bunch of alcohol at the bar, if the bar then serves them another drink or additional drinks and that increases their level of intoxication and then that person goes out and hurts an innocent third-party, then the bar is liable. A Dram Shop claim is an additional claim against the bar, tavern or restaurant who served the drunk driver. People who get injured by drunk driving accidents are innocent and the accidents are so often times severe that the state of Utah has said, "We wanna make sure that those innocent people, that those victims are fully compensated. So we're gonna setup an additional claim they can make, not only against the drunk driver, but also against the company who served alcohol to the drunk driver." So the goal is not only to allow victims to be compensated, but to make servers of alcohol responsible in how they serve people and to ultimately limit the number of drunk driving accidents and to protect the public.
Cutt, Kendell & Olson