A federal judge in eastern Pennsylvania is set to hear a lawsuit by students who say a school district's transgender locker room policy violates their privacy and amounts to sexual harassment.

The Alliance Defending Freedom, a conservative group representing the four Boyertown Area School District students sued in October.

The original plaintiff, identified as Joel Doe, was changing into gym clothes in the boys' locker room when he saw a student, wearing shorts and a bra, who had recently begun transitioning from female to male. The new plaintiffs say their rights to not undress in front of someone of the opposite sex are being violated.

The district says its policy allowing students to use facilities corresponding to their stated gender identity are legal.

A federal judge in Easton will hear the case Monday.