Dr. Stewart serves as the Chair of the Department of Surgery at the University of Texas Health Science Center at San Antonio (UTHSCSA). He holds the Jocelyn and Joe Straus Endowed Chair in Trauma Research and is the Program Director of the Surgical Critical Care Fellowship at the UTHSCSA.

He received his medical degree and residency training at the same institution and completed a Trauma & Critical Care Fellowship at the University of Tennessee-Memphis. He is the Board Chair of the South Texas Regional Advisory Council for Trauma (STRAC), the immediate Past Chairman of the National Trauma Institute (NTI) and the immediate Past Region VI Chief of the American College of Surgeons Committee on Trauma. He serves on the Texas Governor's EMS and Trauma Advisory Council (GETAC), and is the Chair of the GETAC Trauma Systems Committee.