Three eighth-graders from northwest Indiana who say they were expelled after joking on Facebook about which of their classmates they would like to kill asked a federal judge Wednesday to order the district to allow them to return to school, the Associated Press reports. The American Civil Liberties Union of Indiana filed a lawsuit on behalf of the three 14-year-old girls in federal court in Hammond, claiming that Griffith Public Schools violated the students’ free-speech rights. The girls were suspended and later expelled in January for the remainder of the school year after a classmate’s mother alerted officials at Griffith Middle School to the girls’ Facebook posts, the lawsuit says. The suit says school officials told the girls they had violated school policy against bullying, harassment and intimidation…