We have smart serve over here in Canada, basically it says that if I serve you, be it 1 drink or 12, while you are under the influence I am responsible as the server. Note it says that, if it has been tested legally, I am unsure.
I hate this system, if a person is not responsible enough to say "I drove my car into a tree cause I had 6 beer, hopped into it and drove" then they should not drink. People with the mentality of shift it to the servers and staff are going to lead to a world where every time you ingest alcohol, your watch beeps, if you hit a limit your car will not unlock.
How can you expect a server to keep track of the numerous patrons, their drinks and then watch what they do as they leave the door? For that matter, how are we to magically know you had 4 beer in the house before you came, different people react differently, some are overt and some never change from the normal. Yes if my regulars are there I watch them and know their habits and that they cab or one of the wives comes for them, then again they are my regulars, the random Joe off the street though is the wildcard for me constantly.
Time for the people of the world to wake up and accept responsibility for their own actions.