Tex. Util. Code § 36.151
(a) If the regulatory authority, on its own motion or on complaint by an affected person, after reasonable notice and hearing, finds that the existing rates of an electric utility for a service are unreasonable or in violation of law, the regulatory authority shall:
Acts 1997, 75th Leg., ch. 166, Sec. 1, eff. Sept. 1, 1997.