Idaho Code § 32-202

Any unmarried male of the age of eighteen (18) years or older, and any unmarried female of the age of eighteen (18) years or older, and not otherwise disqualified, are capable of consenting to and consummating marriage. A minor under eighteen (18) and not less than sixteen (16) years of age may not contract marriage with a person of the age of majority where there is an age difference of three (3) years or greater between them. No marriage license for a minor under the age of eighteen (18) and not less than sixteen (16) years of age shall be issued where there is such an age difference between the parties. Provided that if the male party to the contract is under the age of eighteen (18) and not less than sixteen (16) years of age, or if the female party to the contract is under the age of eighteen (18) and not less than sixteen (16) years of age, the license shall not be issued except upon the consent in writing duly acknowledged and sworn to by the father, mother, or guardian of any such person if there be either, and provided further, that no such license may be issued, if the male be under eighteen (18) and not less than sixteen (16) years of age and the female under eighteen (18) and not less than sixteen (16) years of age, unless each party to the contract submits to the county recorder his or her original birth certificate, or certified copy thereof or other proof of age acceptable to the county recorder. Where the female is under the age of sixteen (16), or the male is under the age of sixteen (16), the license shall not be issued.