The Taxing Reason Why the Alcohol Content In Spirits Became Known as Proof

Simon Whistler, host of the informative video series “Today I Found Out” shares the historical manner in which the alcohol content within a spirit was determined and how this determination was all the “proof” needed for the King to charge higher taxes.

The process began in England around the 16th century. Its original purpose was not consumer protection, but rather to ensure that the state (read: the King) collected the proper amount of taxes on the sale of the product (alcohol, called proof spirits, was taxed at a higher rate). The first method was imprecise at best, and involved soaking a gun pellet in the liquid, and then trying to light it on fire; if it burned, it was classified as a proof spirit.