Myself and my husband came here for a few drinks one night during our honeymoon visit to San Diego. As we got to the bar to order we were asked if we had official identification, which was not a problem as we are 28 and 30 years old and are familiar with the US policy on this. We proceeded to show our UK driving licences (which we had been using as ID whenever needed over the past 2 weeks in various cities in California). The barman rudely stated that he could not accept this as ID as he wouldn't be able to tell if it was counterfeit. He asked if we had passports with us, which we did not as we would not want to risk losing them on holiday. I'm not sure how he would have known that our UK passports were not counterfeit as he is clearly unfamiliar with the official forms of identification which he requested initially. If you are from outside of the US and below 30 I would be wary of planning to drink here unless you have your passport with you! We went to a different bar across the road called Nine Ten where we were welcomed and had a great time!