Idaho in March became the first state to sign a law—Fairness in Women's Sports Act (Fairness Act)—that prevents biological males from participating in women's sports that are affiliated with the state's public school and higher education systems.

The law, which goes into effect in July, effectively bans transgender girls and women from competing in women's sports and has drawn criticism from LGBT and civil rights advocacy groups.

The law's passage prompted a transgender athlete, represented by the American Civil Liberties Union and Legal Voice, to sue the state governor, Brad Little, and other officials (pdf), arguing that the law "impermissibly discriminates on the basis of sex and transgender status and invades fundamental privacy rights." Joining her in the lawsuit is a biological female who worries that competitors might decide to "dispute" her gender in order to keep her from playing soccer.