Washington Constitution Art. 12, § 22. Monopolies and Trusts

Monopolies and trusts shall never be allowed in this state, and no incorporated company, copartnership, or association of persons in this state shall directly or indirectly combine or make any contract with any other incorporated company, foreign or domestic, through their stockholders, or the trustees or assignees of such stockholders, or with any copartnership or association of persons, or in any manner whatever for the purpose of fixing the price or limiting the production or regulating the transportation of any product or commodity. The legislature shall pass laws for the enforcement of this section by adequate penalties, and in case of incorporated companies, if necessary for that purpose, may declare a forfeiture of their franchises.