It is said that you can tell the quality of scotch by its age, this is in every count of the word maturity. Law states that all blends must indeed mature for a minimum of three years, however for a great many years, these blends have been idling for approximately eight years.
The distillers have found the longer it sits and matures, the better the product. As this scotch sits in its casks, it is constantly changing. The alcohol level drops for every year that it sits in its cask, and what is know as Angels share is developed, where the alcohol is absorbed into the oak casks pours.
The casks that we speak of are of the used variety, due to the fact that new casks would change the taste of the scotch dramatically, hence altering its character.
A law in the US states that for the production of Bourbon, or Tennessee whiskey, only new casks are to be used. The use of these new casks introduces a vanilla taste into the blend. There are some blends as old as 30 years or more, happy hunting for that elusive and pricey item.