Oregon Revised Statutes Labor and Employment; Unlawful Discrimination § 663.155

It is an unfair labor practice for a labor organization and an employer to enter into a contract or agreement, express or implied, whereby the employer ceases or refrains, or agrees to cease or refrain, from handling, using, selling, transporting or otherwise dealing in any of the products of any other employer, or to cease doing business with any other person. Any contract or agreement entered into after January 1, 1972, containing such an agreement is to such extent unenforceable and void.