Key regulations defining Irish whiskey and its production are established by the Irish Whiskey Act of 1980, and are relatively simple (for example, in contrast with those for Scotch whisky, Bourbon whiskey, or Rye whiskey). They can be summarised as follows:
- Irish whiskey must be distilled and aged in the Republic of Ireland or in Northern Ireland.
- The contained spirits must be distilled to an alcohol by volume level of less than 94.8% from a yeast-fermented mash of cereal grains (saccharified by the diastase of malt contained therein, with or without other natural diastases) in such a way that the distillate has an aroma and flavour derived from the materials used.
- The product must be aged for at least three years in wooden casks.
- If the spirits comprise a blend of two or more such distillates, the product is referred to as a "Blended" Irish whiskey.