Attorney General Ken Paxton of Texas sued a Dallas pediatrician on Thursday, accusing her of providing gender transition treatment to minors in violation of a 2023 state law. Mr. Paxton described the suit as the state’s first enforcement action under the new law.

The doctor, May C. Lau, is an associate professor in the department of pediatrics at University of Texas Southwestern Medical Center, a state school and medical research institution. She also treats young patients at Children’s Health in Dallas, which has ties to UT Southwestern, and has worked at a clinic for transgender adolescents that closed in 2021 under pressure from Texas officials.