Oregon Revised Statutes Domestic Relations § 106.050

(1) The county clerk may accept any reasonable proof of the applicant's age satisfactory to the clerk. The clerk may require proof of age by affidavit of some person other than either of the parties seeking the license if the clerk deems it necessary in order to determine the age of an applicant to the clerk's satisfaction.

(2) If an applicant for a marriage license is less than 18 years of age, the applicant must file with the county clerk an affidavit of some person other than either of the parties seeking the license showing the facts other than age necessary to be shown under ORS 106.060 in the particular case, except the consent of the parent or guardian required by ORS 106.060 shall not be part of the affidavit. The affidavit is sufficient authority to the clerk, so far as the facts stated therein, for issuing the license.