Wyo. Stat. § 37-3-101
All rates shall be just and reasonable, and all unjust and unreasonable rates are prohibited. A rate shall not be considered unjust or unreasonable on the basis that it is innovative in form or in substance, that it takes into consideration competitive marketplace elements or that it provides for incentives to a public utility. Except as otherwise provided in W.S. 15-7-407, no public utility shall in any manner charge, demand, collect or receive from any person greater or less or different compensation for any service rendered or to be rendered by the public utility than is charged, demanded, collected or received by the public utility from any other person for a like and contemporaneous service under similar circumstances and conditions. The commission may determine that rates for the same service may vary depending on cost, the competitive marketplace, the need for universally available and affordable service, the need for contribution to the joint and common costs of the public utility, volume and other discounts, and other reasonable business practices. Nothing in this title shall prohibit any public utility from furnishing free or reduced rate service to its current or pensioned employees and dependent family members under rates approved by the commission.
W.S. 37-3-101