They said that the state law, signed by Republican Governor Brad Little in March, illegally discriminates on the basis of gender identity and violates students' right to privacy.
Idaho's bathroom bill allows students to sue schools for $5,000 if they encounter a transgender student in a bathroom the law forbids.
That effectively puts a "bounty" on transgender students and encourages others to search them out, the lawsuit said.
The new law says schools must provide a "reasonable accommodation" for transgender students unwilling or unable to use their assigned bathroom.
Federal courts have been divided on school policies requiring transgender students to use the restroom corresponding to their birth sex, with the Richmond, Virginia-based 4th U.S.
Persons:
Queen Mary, Stephane Mahe, David Nye, Peter Renn of, Raul Labrador, Rebecca Roe, Brad Little, Brendan Pierson, Jonathan Oatis
Organizations:
Justice, REUTERS, U.S, District, Peter Renn of Lambda, Republican, Circuit, Appeals, Thomson
Locations:
Brittany's, Rennes, France, Idaho, Richmond , Virginia, Virginia, Atlanta, Florida, New York