Tex. Ins. Code § 1305.304

Each network shall adopt treatment guidelines, return-to-work guidelines, and individual treatment protocols. The treatment guidelines and individual treatment protocols must be evidence-based, scientifically valid, and outcome-focused and be designed to reduce inappropriate or unnecessary health care while safeguarding necessary care. Treatment may not be denied solely on the basis that the treatment for the compensable injury in question is not specifically addressed by the treatment guidelines used by the insurance carrier or network.