Marnie McCormick and David Duggins represented a gas utility in a challenge that cities and state agencies brought against the company’s rate. Specifically, the cities and state agencies challenged the Railroad Commission’s authority to adopt a formula rate that results in periodic changes to customer charges without successive traditional ratemaking proceedings. Though the district court sustained the challenge of the municipalities and state agencies, the utility prevailed in the Third Court of Appeals, and the Texas Supreme Court ultimately upheld the rate in a unanimous opinion.