On May 4, 1964, the United States Congress recognized Bourbon Whiskey as a “distinctive product of the United States.” The Federal Standards of Identity for Distilled Spirits (27 C.F.R. 5.22) state that bourbon must meet these requirements:
* Bourbon must be made of a grain mixture that is at least 51% corn (maize).
* Bourbon must be distilled to no more than 160 (U.S.) proof (80% alcohol by volume).
* Neither coloring nor flavoring may be added.
* Bourbon must be aged in new, charred oak barrels.
* Bourbon must be entered into the barrel at no more than 125 proof (62.5% alcohol by volume).
* Bourbon, like other whiskeys, may be bottled at not less than 80 proof (40% alcohol by volume.)
* Bourbon that meets the above requirements and has been aged for a minimum of two years may (but is not required to) be called Straight Bourbon.
* Straight Bourbon aged for a period less than four years must be labeled with the duration of its aging.
* If an age is stated on the label, it must be the age of the youngest whiskey in the bottle.
* Only whiskey produced in the United States can be called bourbon.
JD is 80% corn so they prefer to call it "Corn Whiskey" or sour mash. I think it's voluntary...
Too much information on the web to determine fact over fiction...