We have been going out often to a funky place that doesn't serve alcohol in Burbank and always bring a Bass Ale 12-pak. Once in a while we want to bring a decanter with our Margaritas. Is this legal?
Also, can you legally b.y.o.b. to your local taco stand?
Check with the local department of Alcoholic Beverage Control. I worked at the one in San Diego and there were some establishments that were precluded entirely from allowing alcoholic beverages if there was no license. I knew then that there were some different laws put into place for Los Angeles. I worked there almost 15 years ago so I am sure that laws have changed as well.
What ever you do, DO NOT rely on the restaurant owner to tell you the truth. Sometimes they don't know the law or sometimes they do and are breaking the law. I can't tell you how many places I helped shut down because of such infractions.
Go to the source if you want to be 100% sure. (And maybe let us know what you found!)