At a news conference in Denver, the Transgender Legal Defense and Education Fund said it has filed a complaint on behalf of Coy Mathis with the Colorado Civil Rights Division, CNN reported. Lawyer Michael Silverman called the action a "test of Colorado's Anti-Discrimination Act."
"For many transgender people, discrimination is a daily part of life. Unfortunately for Coy, it has started very early," Silverman said.
Coy's parents pulled her out of Eagleside Elementary School in December after the Fountain-Fort Carson School District said she would have to use the boys' restroom, the school nurse's bathroom or a gender-neutral toilet and have been schooling her at home.
"We were very confused because everything was going so well, and they had been so accepting, and all of a sudden it changed and it was very confusing and very upsetting because we knew that, by doing that, she was going to go back to being unhappy," she told CNN. "It was going to set her up for a lot of bad things."
Coy's parents say she began identifying herself as a girl very young. For almost a year, she has been wearing girls' clothes.
The school district said officials believe other students and their parents would be uncomfortable as Coy got older to have someone with male genital organs using a girls' bathroom.
Pregnant Mila Kunis wins 'Best Villain' at MTV Movie Awards
Biologists detail four new deep-sea 'killer sponges'