Oregon Revised Statutes Labor and Employment; Unlawful Discrimination § 663.140

(1) An employer or self-employed person to join a labor or employer organization or to enter into an agreement that is prohibited by ORS 663.155;

(2) A person to cease using, selling, handling, transporting or otherwise dealing in the products of any other producer, processor or manufacturer, or to cease doing business with any other person, or forcing or requiring any other employer to recognize or bargain with a labor organization as the representative of employees of the employer unless such labor organization has been certified as the elected representative of such employees. However, nothing in this subsection makes unlawful, where not otherwise unlawful, any primary strike or primary picketing;

(3) An employer to recognize or bargain with a particular labor organization as the representative of employees of the employer if another labor organization has been certified as the elected representative of such employees; or

(4) An employer to assign particular work to employees in a particular labor organization or in a particular trade, craft or class rather than to employees in another labor organization or in another trade, craft or class, unless the employer is failing to conform to an order of the Employment Relations Board or certification of the conciliator determining the bargaining representative for employees performing the work.