You'd have to look at your State Department's website to determine the legal limit of importing alcohol and the same is true of exporting.

I always bring back several bottles of good Scotch from Scotland and European wine when I travel, but I have never brought any alcohol into a foreign country. I guess there is no reason to bring it IN when you can just buy some when you get there.

I know for sure that it is illegal to drink alcohol ON BOARD the flight that was brought onto the plane by any passenger including yourself. In the USA you could face federal charges if you were caught, but it is more likely they;d just deport you if it was a 1st offense (being you are a UK citizen.)