Arizona Superintendent of Public Instruction Tom Horne is pushing back on a proposed rule from the U.S. Department of Education.

The rule would keep schools from adopting one-size-fits-all bans on transgender and nonbinary students in sports, but allows schools to make some exceptions. 

The department said that could be for ensuring competitive fairness or preventing sports-related injuries.

But Horne said there is just no circumstance where it makes sense for a "biological boy" to play on a girls’ team.

“If the boy’s biology does not give an advantage, then have a mixed-gender team," he said. "The whole reason we separate boys teams from girls teams is because of boys’ muscle structure and bone structure.”

The department is accepting public comment on the proposal for 30 days.