I don't know, we're talking possibilities. I'm not an attorney. But, typically, laws that apply to taverns stress they are negligent if they do not ask for proof of age (when appropriate), if they serve obviously inebriated customers (or customers that could be reasonably assumed to be so, i.e. have been served 3 drinks w/in one hour period), or if they serve after closing hours.
I am attempting to disagree with the notion that taverns bear no responsibility. Knowing what we know about alcoholism, and individual responsibility in general, it is unreasonable to expect customers to make responsible decisions--- a sober and law-abiding server is a better bet. Those who profit bear responsibility for the outcomes of their actions. It isn't either/or but rather both customer and tavern owner bearing responsibility.