Oregon Revised Statutes Elections § 249.008

(1) Except as provided in subsection (2) of this section, before a nominating petition, minutes of an assembly of electors, or petition by individual electors is offered for filing, the county clerk of each county in which the signatures were secured shall compare the signatures of electors on the petition or minutes with the signatures of the electors on the elector registration cards. Any petition or minutes submitted for verification under this section shall contain only original signatures. The county clerk shall attach to the petition or minutes a certificate stating the number of signatures believed to be genuine. The certificate is prima facie evidence of the facts stated in it. A signature not included in the number certified to be genuine shall not be counted by the officer with whom the petition is filed. No signature in violation of the provisions of this chapter shall be counted.

(2) If the total number of signatures presented to a county clerk for verification is 15,000 or more, the county clerk may use a statistical sampling technique authorized by the Secretary of State to verify the signatures. The sample shall be drawn from at least 100 percent of the number of signatures required for nomination.

(3) After signatures of electors on a nominating petition, minutes of an assembly of electors or petition by individual electors are submitted for verification, no elector who signed the petition or minutes may remove the signature of the elector from the petition or minutes.