Bourbon, America’s native spirit, has a rich history dating back to the late 18th century. Though it shares similarities with other types of whiskey, bourbon is defined by a strict set of legal standards that distinguish it from its counterparts. These rules ensure that the quality and character of bourbon remain consistent and true to tradition. Here are the five rules that every bourbon must adhere to:

1. Bourbon Must Be Made in the United States

Bourbon is often associated with Kentucky, but legally, it can be produced anywhere within the United States. That said, Kentucky is still the heart of bourbon production, thanks to its ideal climate and limestone-rich water, which many distillers claim enhances the flavor. This law, codified in 1964 when bourbon was declared “America’s Native Spirit,” ensures bourbon remains a distinctly American product.

2. The Mash Bill Must Contain at Least 51% Corn

The grain recipe, or “mash bill,” of bourbon must consist of at least 51% corn. This corn gives bourbon its characteristic sweetness and smoothness, setting it apart from other whiskeys, like rye or scotch. While the remaining 49% of the mash bill can include other grains—typically rye, wheat, and malted barley—it is the predominance of corn that makes bourbon unique.

 3. Aged in New Charred Oak Barrels

One of the most defining characteristics of bourbon is its aging process. By law, bourbon must be aged in new, charred oak barrels. The interior of these barrels is set on fire before the aging process, caramelizing the wood sugars and imparting distinct flavors like vanilla, caramel, and spice to the bourbon. These flavors are vital to the final profile of the spirit, with the aging process often being a key factor in determining a bourbon’s quality.

4. Distilled to No More Than 160 Proof

Bourbon must be distilled to no more than 160 proof (or 80% alcohol by volume). This ensures that the final product retains more of the grain character and flavor. Higher-proof distillation strips away many of the flavorful congeners, producing a more neutral spirit like vodka. By capping the distillation proof, the law guarantees that bourbon remains a flavorful and full-bodied whiskey.

5. Bottled at a Minimum of 80 Proof

After the aging process, bourbon must be bottled at no less than 80 proof (40% alcohol by volume). This minimum ensures that even the lightest bourbons maintain enough strength to deliver the characteristic flavors and body associated with the spirit. Additionally, bourbon can’t be entered into the barrel at more than 125 proof, another measure to protect the integrity of its flavor.

Bourbon’s unique qualities stem from the adherence to these strict production standards. While distillers are free to innovate within these rules—experimenting with different mash bills, aging times, rickhouse placement & char levels—the core guidelines ensure that bourbon retains its identity as a distinctly American spirit. Whether you’re sipping a small-batch bourbon or enjoying a classic Old Fashioned, you can thank these five essential rules for maintaining the rich tradition and flavor of this iconic whiskey.