The most legally defined whiskey in the world — and the law is the recipe
Bourbon's strict legal requirements don't limit it — they create it. Every rule in the code produces a flavour. Understanding the law is understanding the whiskey.
A legal definition that doubles as a flavour specification
Bourbon is an American whiskey with more legal requirements than any other style in the world. It must be made in the United States from a grain bill of at least 51% corn, distilled to no more than 160 proof, aged in new charred American white oak containers, and bottled at no less than 80 proof. No colouring, flavouring, or additives are permitted.
These are not arbitrary bureaucratic rules. Each requirement directly creates a flavour characteristic. The corn provides sweetness. The new charred oak provides vanilla, caramel, and wood spice. The entry proof limit preserves grain character. The bottling minimum ensures enough alcohol to carry the flavour. The law is, in effect, a recipe.
The 7 legal requirements
Produced in the United States — bourbon cannot legally be made anywhere else.
Mash bill of at least 51% corn — the remainder is typically rye or wheat, plus malted barley.
Distilled to no more than 160 proof (80% ABV) — keeps grain character intact.
Entered into the barrel at no more than 125 proof (62.5% ABV).
Aged in new, charred oak containers — the barrel can never be reused for another batch of bourbon.
No added colouring, flavouring, or blending materials — what's in the bottle came from the grain and the wood.
Bottled at 80 proof (40% ABV) or more.
“All bourbon is whiskey, but not all whiskey is bourbon — and no, it doesn't have to come from Kentucky. It just usually does.”
The Kentucky question
Three grains, one dominant
Every bourbon mash bill is built from the same three grains in different proportions. Corn always leads; the second grain — rye or wheat — sets the style's personality, and a small amount of malted barley provides the enzymes needed to convert starch to sugar.
Corn
Minimum 51%
The mandatory majority grain. Contributes sweetness and body — the higher the percentage, the softer and sweeter the whiskey.
Rye or wheat
The flavour grain
Rye brings pepper and spice; wheat brings softness and gentle sweetness. This choice defines whether a bourbon reads as spicy or mellow.
Malted barley
The workhorse
Usually a small percentage. Supplies the enzymes that convert starch into fermentable sugar — rarely tasted directly.
New wood, once only
Unlike Scotch, which reuses ex-bourbon and ex-sherry casks for decades, bourbon law requires a fresh, charred, new American white oak barrel for every single batch — used exactly once.
Char 1
“Light char” — 15 seconds. Subtle wood influence, rarely used alone.
Char 2
“Medium char” — 30 seconds. Balanced caramel and spice notes.
Char 3
“Alligator char” — 55 seconds. The most common char level for bourbon; deep caramelisation.
Extra char
70+ seconds. Rare, intense char used by a handful of producers for bold, smoky bourbons.
Five ways to be bourbon
Straight Bourbon
Aged at least 2 years, no added colouring or flavouring of any kind. Most premium bourbon is “straight.”
Bottled-in-Bond
A single distillery, a single season, aged 4+ years in a federally bonded warehouse, bottled at exactly 100 proof. The strictest sub-category.
Single Barrel
Bottled from one barrel rather than a blended batch. Every bottle from a different barrel will taste slightly different.
Wheated Bourbon
Uses wheat instead of rye as the secondary grain — softer, rounder, less spicy. Pappy Van Winkle is the famous example.
High Rye Bourbon
A higher-than-usual rye percentage (often 20-35%) for a spicier, more assertive profile that leans toward rye whiskey.
From bar-shelf to allocated
Entry level
£18–£30
Widely available, everyday sipping and mixing bourbons — Buffalo Trace, Wild Turkey 101, Evan Williams Black.
Mid-range
£30–£50
Age-stated and single-barrel expressions — Eagle Rare, Four Roses Single Barrel, Woodford Reserve Double Oaked.
Premium
£50–£120
Older age statements and cask-strength bottlings — Elijah Craig Barrel Proof, Four Roses Small Batch Select.
Allocated
£120+
Limited annual releases that sell out on announcement — George T. Stagg, Pappy Van Winkle, William Larue Weller.
Who makes it
Buffalo Trace
Frankfort, Kentucky. The most decorated distillery in America — home to Buffalo Trace, Eagle Rare, Blanton's, and the allocated Antique Collection.
Heaven Hill
Bardstown, Kentucky. Family-owned, second-largest holder of ageing bourbon stock in the world — Elijah Craig, Larceny, Evan Williams.
Four Roses
Lawrenceburg, Kentucky. Uniquely uses 2 mash bills × 5 yeast strains — 10 distinct bourbon recipes blended to taste.
Wild Turkey
Lawrenceburg, Kentucky. High-rye, higher-proof house style under master distiller Jimmy Russell — over 65 years at the distillery.
Picking your first bottle
Start with a standard Straight Bourbon
Buffalo Trace, Four Roses Yellow Label, or Wild Turkey 101 all show the classic profile without a premium price tag.
Decide rye-forward or wheated
If you like spice, look for “high rye” on the label. If you prefer soft and sweet, look for “wheated.”
Try Bottled-in-Bond for guaranteed value
The 100-proof, 4-year-minimum standard means a Bottled-in-Bond bottle is almost never a bad choice for the price.
Bourbon reviews on Caskable
All reviews →Bourbon: quick answers
Does bourbon have to be made in Kentucky?
No. Bourbon can legally be made anywhere in the United States. Kentucky produces roughly 95% of the world's bourbon by volume, thanks to its limestone-filtered water and climate, but the law makes no geographic requirement beyond “made in the USA.” Distilleries in Texas, New York, and Colorado all make legitimate bourbon.
What's the difference between bourbon and Tennessee whiskey?
Tennessee whiskey meets every legal requirement of bourbon, plus one extra step: the Lincoln County Process, which filters the new-make spirit through a thick layer of sugar-maple charcoal before it goes into the barrel. Jack Daniel's and George Dickel both qualify as bourbon by law but choose to label themselves Tennessee whiskey instead.
Why is bourbon getting more expensive?
Demand has outpaced supply for over a decade. Bourbon has to age for years before it can be sold, so distilleries can't simply ramp up production to meet a sudden surge in popularity — what's being bottled today was laid down back when demand was much lower. Allocated releases in particular have become collector items, driving secondary-market prices well above retail.
What does “bottled-in-bond” actually guarantee?
It's a federal designation from 1897 — one of the oldest consumer protection laws in the US. It guarantees the whiskey came from one distillery, one distiller, in one season, was aged at least 4 years in a federally bonded warehouse, and is bottled at exactly 100 proof. It says nothing about quality directly, but the constraints tend to produce reliably well-made whiskey at a fair price.
Is older bourbon always better?
No — unlike Scotch, bourbon ages in a much hotter, more variable climate, so the wood influence moves faster and can overwhelm the spirit well before 15-20 years. Many distillers consider 6-12 years the sweet spot for most mash bills. Extreme age statements are often more about scarcity and marketing than a guarantee of better flavour.
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