In response to a request from Sen. Brian Birdwell, AG Ken Paxton has issued an opinion finding that, as school marshals can carry handguns pursuant to “written regulations adopted by the board of trustees…a court would likely conclude that Education Code subsection 37.0811(c) authorizes a board of trustees to adopt regulations that allow a school marshal to duty belt carry a handgun.”
For more information see the opinion here (PDF) and Sen. Birdwell’s request here (PDF).