Yes, Beer's Law is used for measuring the amount of alcohol in a sample of an alcoholic beverage. We did it in a lab in Chem 102. (It was dodgy back then for us not-allowed-to-drink students to be analyzing samples of beer and wine; today I suspect it wouldn't be allowed at all. Even though a taste test was not part of the analysis.) Unfortunately, I don't remember any of the chemistry involved. I suppose I could look at the Wikipedia entry.