Oregon Revised Statutes Labor and Employment; Unlawful Discrimination § 663.035

(1) Upon the filing with the Employment Relations Board by 40 percent or more of the employees in a bargaining unit covered by an agreement between their employer and a labor organization requiring membership as a condition of employment, of a petition alleging that they desire that the authority of the labor organization to make such an agreement be rescinded, the board shall direct the conciliator to take a secret ballot, marked at the place of election, of the employees in the unit and to certify the results thereof to the labor organization and to the employer.

(2) No election shall be conducted pursuant to this section in a bargaining unit or a subdivision within which, in the preceding 12 months, a valid election has been held.