Idaho Constitution Art. XI, § 18. Combinations in restraint of trade prohibited

That no incorporated company or any association of persons or stock company, in the state of Idaho, 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 in any manner whatsoever, for the purpose of fixing the price or regulating the production of any article of commerce or of produce of the soil, or of consumption by the people; and that the legislature be required to pass laws for the enforcement thereof, by adequate penalties, to the extent, if necessary for that purpose, of the forfeiture of their property and franchise.