If any person intending to marry and seeking a license therefor shall be under 18 years of age, and shall not have been previously married, the said Mayor or Clerk shall not issue such license unless a parent, or, if there be neither father nor mother, the guardian, if there be such, shall consent to such proposed marriage, either personally to the Mayor or Clerk, or by an instrument in writing attested by a witness and proved to the satisfaction of the Mayor or Clerk.
D.C. Code § 46-411