Texas Tech University System Chancellor Tedd Mitchell issued guidance Thursday instructing faculty on all five campuses to "comply with laws" and recent executive orders recognizing just two genders in academic discussions.

In a letter, Mitchell said the universities are "required to comply with both state and federal law, executive orders, and directives issued by the President of the United States and the Governor of Texas."

"Current state and federal law recognize only two human sexes: male and female, as outlined in House Bill 229, Governor's Letter, and Executive Order," the letter added.

Brian Evans, president of the Texas conference of the American Association of University Professors, said the move would impair classroom conversations with students.

"On a banned topic, the instructor cannot lead a discussion," he told The New York Times. "They'd either have to be silent, or leave the room, or redirect the conversation to another topic. This is crazy."

Mitchell's letter was addressed to the presidents of Angelo State University, Texas Tech University, Texas Tech University Health Sciences Center, Texas Tech University Health Sciences Center El Paso, and Midwestern State University.