The parents of a trans girl who was barred from using the female toilets in her school have filed a civil lawsuit following the school’s refusal to mediate with them over the issue.

Coy Mathis, a 6 year old student at Eagle Elementary School in Fountain, Colorado, was born anatomically male but expressed herself as female from a young age.

Her parents, Kathryn and Jeremy Mathis, say that from the age of 18 months Coy showed signs of depression when asked to wear boys’ clothes or act boyishly, and she told her parents that she was a girl.

After seeking medical advice they learned Coy had gender dysphoria, and followed the recommendations of doctors who told them she should be allowed to live as a girl.

At first this recommendation was also supported by Eagle Elementary, who registered Coy as a female student and allowed her to use the girl’s bathrooms while in Kindergarten.

However, in December 2012 the school told Coy’s parents she would no longer be allowed to use the girls’ bathrooms and would have to use facilities in the nurses’ offices, teachers’ bathrooms, or boys’ bathrooms instead.

“Coy is not sick, she is not an adult, and she is not a boy,” her parents responded.

They took Coy out of Eagle Elementary for homeschooling and in February lodged an official complaint against the school.

Eagle Elementary has rejected calls to mediate over their treatment of Coy, prompting her parents to file a civil rights lawsuit.

“If the school separates her from all her classmates to use the bathroom, they are singling her out for mistreatment, and teaching her classmates that it’s okay to discriminate. We are saddened that her school will not even come to the table to talk about this issue,” they said.

The Transgender Legal Defense and Education Fund (TLDEF) have pointed out that Colorado’s laws prohibit discrimination against transgender pupils. They said: “We are shocked that her school will not even meet to talk about this so that Coy can quickly return to school. Nothing should be more important to a school than ensuring that students can attend safely and without discrimination.”

TLDEF Director Michael Silverman added: “For many transgender people, discrimination is a daily part of life. Unfortunately for Coy, it has started very early.”

The school have said that their decision “took into account not only Coy, but other students in the building, their parents and the future impact a boy with male genitals using a girls’ bathroom would have as Coy grew older”.

Kathryn Mathis has dismissed the school’s response, saying they should not discriminate against Coy based on speculations.

“Her body development is none of their business. That is up to her and her doctors in the future,” she said.

“Right now we need to be protecting a 6-year-old, not a middle-schooler or a high-schooler.”

The case will now be investigated by the Civil Rights Division (CRD), a regulatory agency in Colorado.

The CRD will have 180 days to investigate before making a ruling, which can then be appealed by the party that is ruled against. From there the case will be referred to the courts.