The lawsuit was filed Wednesday in federal court on behalf of a former Elwood High School student identified only as John Doe.
The lawsuit alleges Doe was molested by former teacher Michael Kluck, who hired by Elwood in 1992.
The lawsuit said that the boy dropped out of school after being molested.
When it was later learned that Doe allegedly had been molested by Kluck, school and insurance officials convinced him to sign a form saying he had not been molested.
They told Doe that by signing the form, he would avoid the embarrassment of testifying at the trial involving another student who allegedly had been molested.
That, according to the lawsuit, prevented Doe from bringing his own lawsuit.
Officials at the school and the insurance company declined immediate comment.