The ACLU filed an amicus curiae brief in support of R.M.A, a transgender student in the Blue Springs School District.
R.M.A. brought a charge of sex discrimination under the Missouri Human Rights Act against his school following the school's refusal to allow R.M.A. to use the boy's restrooms and locker room, instead requiring him to use a separate space. The ACLU of Missouri filed an amicus curiae brief detailing the positive effects of allowing transgender students to use the facilities that align with their gender identity, and supporting an interpretation of the Missouri Human Rights Act that protects transgender individuals under laws prohibiting sex discrimination. The case was eventually brought to the Missouri Supreme Court, which issued an opinion on February 26th, 2019. The Supreme Court found that R.M.A.'s gender identity was protected under the Missouri Human Rights Act, and that he should be allowed to use the facilities that align with his gender.
Find the Legal Glossary here: https://www.aclu-mo.org/en/node/124