Definitions Make Differences
Initially, Proctor & Gamble successfully argued that Pringles should be exempt from the tax on the basis that the Pringle is a moulded dough product rather than a potato chip product (or potato crisp if you are from the UK) and that the Pringle is made from less than 50% potato ingredients; however, the taxman appealed.
On appeal, the taxman won resulting in back taxes due from Proctor & Gamble for an amount in excess of $150,000,000. Proctor & Gamble found out that a definition can make a very big difference.
Pringles are made from 42% potato flour with other main ingredients including wheat starch.