The American Civil Liberties Union of Illinois says it will seek to intervene in a federal lawsuit seeking to block a suburban Chicago school district from allowing a transgender student to use a girls’ locker room and restroom.

ACLU spokesman Edwin Yohnka said Tuesday the group will file a motion in the coming days to intervene on behalf of a group of parents, students and others opposed to the lawsuit. The complaint filed May 4 by the Alliance Defending Freedom and Thomas More Society on behalf of 51 families against Palatine-based District 211 and the U.S. Department of Education.

The ACLU has represented the student who was born male but identifies as female and won access to girls’ facilities at William Fremd High School.