Idaho Code § 23-1013: Restrictions concerning age.

Any person who is nineteen (19) years of age or older may sell, serve, possess or dispense beer in the course of his employment, otherwise it shall be unlawful for any person to sell, serve or dispense beer to or by any person under twenty-one (21) years of age, proof of which, shall be a validly issued state, district, territorial, possession, provincial, national or other equivalent government driver’s license, identification card or military identification card bearing a photograph and date of birth, or a valid passport.