"Did intoxication play a big role in what happen?" asked Brett Rivkind, a Miami maritime lawyer who represents the Smith family. "And if so, then you need to look at maritime law and legal responsibility, which holds the cruise line responsible to adequately supervise the serving of alcohol and alcohol consumption aboard their ship."
There are two relevant nuances.
1. In this case, it does not appear that the fact that Mr. and Mrs. Smith were both quite drunk was in any way material to the disappearance.
2. In this case, it does not appear that the cruise line served the alcohol that they were drinking.
I believe that Mr. Rivkind does not have a case.