Jack Daniels is a whiskey, and most of it is made out of corn and maize. These two grains are gluten-free. However, these two grains only make up 51% to 79% of the whiskey. The problem comes when we calculate the remaining percentage. For, a variety of different mash grains may be in use–and a lot of these grains are not gluten-free.
Some people do consider Jack Daniels to be gluten-free, because during the distilling process, all of the gluten is taken out of the whiskey. Some people who require gluten-free diets can still tolerate drinking it–thanks to this process. However, this is entirely based on an individual’s sensitivity. Therefore if one requires a completely gluten-free diet, they should be warned before drinking Jack Daniel’s whiskey.