Gin is defined by the USA's Code of Federal Regulations Title 27, volume 1 as:
Gin is a product obtained by original distillation from mash, or by redistillation of distilled spirits, or by mixing neutral spirits, with or over juniper berries and other aromatics, or with or over extracts derived from infusions, percolations, or maceration of such materials, and includes mixtures of gin and neutral spirits. It shall derive its main characteristic flavor from juniper berries and be bottled at not less than 80 deg. proof. Gin produced exclusively by original distillation or by redistillation may be further designated as `distilled'. `Dry gin' (London dry gin), `Geneva gin' (Hollands gin), and `Old Tom gin' (Tom gin) are types of gin known under such designations.