LOWELL, Ind. (CBS) -- A teenager who recently graduated from high school in northwest Indiana has sued her school, after she was suspended over Twitter comments she made outside of school.

The American Civil Liberties Union filed the federal lawsuit this week on behalf of Delaina Trusty, who graduated last month from Lowell High School.

Trusty claimed she was wrongly punished for her use of Twitter while she was away from school.

The suit alleged she was suspended for one day in February, after sending a tweet to a classmate about a third student, a girl who was dating Trusty's ex-boyfriend.

The message read: "I just stalked your Twitter because I enjoy the fact we share the same hatred for the same girl ;) lol."

She said school officials told her that her "negative encounters" with another student were the reason she was suspended.

The ACLU said Trusty's suspension violated her First Amendment rights because she sent the tweet away from school.

Trusty wants the suspension cleared from her record, fearing it could hurt her chances of getting into college.