Serving alcoholic beverages to guests who show signs of being intoxicated is legal, as long as:
a. the guest has a designated driver
b. the guest leaves his car keys at the bar and agrees to take a cab ride home
c. it is never legal to serve alcoholic beverages to guests who show signs of being intoxicated.
d. they have ordered dessert and are waiting for the final bill.

It is never legal to serve alcoholic beverages to guests who show signs of being intoxicated.

Explanation:

In most of the countries, serving alcoholic drinks to an already intoxicated individual is considered an offence. This means that, apart from checking the age of a person who buys alcohol, the sellers must make sure that the guests do not show signs of intoxication. The server, rather than the customer, is held responsible for making a decision whether or not to serve a particular guest, and thus must look for clues to determine if a guest is drunk or not. Drunk people usually behave disturbingly and, in this way, present a danger to themselves and other people.