On Monday, Idaho became the first state to enact a law protecting equal opportunities for female athletes by using biological sex to determine participation in women’s sports. Though critics such as the American Civil Liberties Union say there is “no data” supporting the law, simple research clearly shows such claims to be false.

Underlying the storied and well-accepted existence of dividing sports based on sex is the basic biological fact that men and women are different and that males have numerous physical features that give them unfair advantages over women in sports.