Today we battle it out with two titans of Irish whisky: Bushmills white label and Jameson Irish. Both being blends they are made from grain whisky (made from any cereal grain, often maize, in a column still) and pot still whisky. To be called ‘pot still’ whisky, the formal rule states (quoted from an excellent article here from Pernod Ricard):
The Irish Whiskey Technical File lists that Irish Pot Still Whiskey must be made from a mash which contains a minimum of 30% malted barley and a minimum of 30% unmalted barley, with up to 5% of other cereals such as oats and rye added if required.
Note the use of unmalted barley, which differentiates Irish from Scotch whisky. Other rules state that the aging must be at least 3 years in oak. Like most Irish whiskies, the pot still component of both are triple distilled. The law states for a blend it must be “a mixture of any two or more of the styles of malt, pot still, and grain whiskey” (source whiskyadvocate).