The Rules of Bourbon: The 6 Federal Laws That Define America’s Native Spirit – 27 CFR § 5.143, 1964 Congressional Act, Bottled-in-Bond

America’s Only Distinctive Native Spirit:
On May 4, 1964, the 88th United States Congress passed Senate Concurrent Resolution 19 (78 Stat. 1208), officially recognizing Bourbon Whisky as a “distinctive product of the United States.” Unlike Scotch or Cognac, which are protected by foreign crowns, bourbon is protected by federal statute. Every bottle must comply with the Standards of Identity set forth in Title 27 of the Code of Federal Regulations.

1
Geographic Boundary: Produced in the United States

By law, bourbon cannot be distilled in Canada, Scotland, Japan, Ireland, or Mexico. Under international trade agreements and NAFTA/USMCA, other nations recognize bourbon as an exclusively American spirit. A distiller in Germany using 70% corn and new charred oak cannot legally sell their spirit as “bourbon” in international commerce.

While federal statute permits bourbon to be crafted anywhere across the United States, Kentucky’s delegation placed the Commonwealth’s stance on the national record during the 2016 convention roll call, introducing Kentucky as “the state that produces all the bourbon fit to drink in the world.”

2
Grain Mashbill: Minimum 51% Corn

Corn provides bourbon with its hallmark body, rich oily texture, and sweet foundation. The remaining 49% of the mashbill consists of “small grains”—rye for peppery herbaceousness, wheat for softness and bread crust, and malted barley, whose natural alpha and beta amylase enzymes convert complex grain starches into fermentable sugars.

3
Distillation Ceiling: Maximum 160 Proof (80% ABV)

Vodka is distilled at 190 proof or higher, stripping out virtually all grain flavor and character. By capping bourbon distillation at 160 proof (with most Kentucky distillers coming off the beer still and doubler between 130 and 140 proof), federal law preserves the volatile flavor compounds (esters, aldehydes, and higher alcohols known as congeners) that give bourbon its agricultural terroir.

4
Barrel Entry Ceiling: Maximum 125 Proof (62.5% ABV)

High-proof alcohol dissolves harsh wood tannins. By forcing distillers to dilute raw spirit down to 125 proof or lower before filling barrels, the water enables sweet wood sugars (hemicellulose, vanillin, and caramel) to dissolve into the liquid during maturation. Brands like Maker’s Mark enter the barrel at a super-low 110 proof to maximize sweetness.

5
Aging Vessel: New, Charred Oak Containers

The barrel must be new and it must be charred on the inside with open flame (typically Level 3 char of 35 seconds or Level 4 “alligator” char of 55 seconds). The char creates a natural activated carbon filter that removes sulfur and harsh compounds while caramelizing the wood’s natural sugars. Once a barrel is emptied, it can never be used to make bourbon again (used barrels are shipped to Scotland, Ireland, or Mexico for tequila).

6
Bottling Floor: Minimum 80 Proof & Zero Additives

Bourbon must be bottled at a minimum of 80 proof (40% ABV). Absolutely zero caramel coloring, sugar, oak flavoring, or blending additives may be introduced. The only permissible addition is pure water to reduce proof.