Key Takeaways
- Federal regulations require bourbon to be made from a grain mix of at least 51 percent corn and aged in new charred oak containers.
- Bourbon must be distilled at no more than 160 proof, enter the container at no more than 125 proof, and be bottled at no less than 80 proof.
- Nothing but water may be added to bourbon, so flavored products such as honey whiskey cannot be sold simply as bourbon.
What makes bourbon bourbon? Is it a style, a tradition, or something the law actually spells out?
Joel Cohen talks with Brian Haara, a Louisville, Kentucky attorney and author of Bourbon Justice: How Whiskey Law Shaped America, about the federal rules that define bourbon, what has to go into it, and what can never be added.
A Heavily Regulated Whiskey
Bourbon is very much a defined term, Haara explains. It has been defined since the 1800s, more loosely at first, and by the 1960s its definition had made its way into the Code of Federal Regulations, where it is heavily regulated. All whiskey is a distillate made from grains such as barley, rye, and corn, and bourbon is one type of whiskey. The starting point of the definition is that bourbon must be made from at least 51 percent corn, making it a majority-corn whiskey.
Proof Limits and New Charred Oak
Haara walks through the proof limits at each stage. Bourbon must be distilled at no higher than 160 proof, because distilling higher strips away grain flavor, and part of what makes bourbon special is that you can taste the corn and rye. It must go into the barrel at no higher than 125 proof, again to allow more interaction with the wood. Proof can rise or fall during aging depending on where the barrel sits in the warehouse; barrels stored higher up tend to gain proof, so a bourbon that entered at 120 proof might reach 137 proof seven years later and be bottled at that strength. It cannot be bottled below 80 proof.
The regulation, he notes, does not actually say barrel. It requires charred new oak containers. Everyone uses barrels, but a bucket made of new charred oak would technically work. New means no previous use. Once emptied, bourbon barrels go on to age Scotch and tequila, so bourbon makers in effect get barrels ready for the rest of the whiskey world. First use gives the spirit more interaction with the char, which releases sugars from the wood and produces a sweeter whiskey than Scotch.
Nothing Added but Water
The restrictions are simple: nothing else may go in. Pure water is the only thing that can be added to bourbon. Other whiskies, such as Scotch, may include coloring and flavoring additives, but bourbon may not. Its flavors must come from the yeast, the distillation, the grains, and the barrel. That is why there is no honey bourbon sold under the bourbon name. Plenty of honey and cinnamon flavored whiskies start with bourbon, Haara explains, and some bourbon is moved into other barrels for finishing, which can add different flavors, but in his view those products are technically no longer bourbon.
What to Know Now
The legal definition Haara describes remains in place. In 2022, the Alcohol and Tobacco Tax and Trade Bureau (TTB) modernized its distilled spirits labeling rules and moved the whisky standards of identity, including bourbon, into a table at 27 CFR 5.143, with the same corn, proof, container, and no-additive requirements. Federal rules also reserve the bourbon name for whisky made in the United States, though it need not come from Kentucky. Cask-finished products are commonly labeled with a description of the extra step, such as bourbon finished in port or wine barrels. TTB has continued to refine whisky categories, adding a standard of identity for American single malt whisky effective January 2025. For consumers, the word bourbon on a label still carries a precise legal meaning.
