The American Civil Liberties Union has challenged New Hampshire's criminal defamation law in the arrest of a man who posted comments saying a police chief "covered up" for a "dirty cop."
The ACLU's federal lawsuit filed Tuesday says the law violates the First Amendment.
The law makes it a misdemeanor for someone who intentionally communicates information known to be false that could expose others to "public hatred, contempt or ridicule."
Exeter police eventually dropped the charge against Robert Frese, who responded to an Exeter News-Letter article, "Retiring Exeter Officer's Favorite Role: Mentoring Youth."
Frese wrote the officer "is the dirtiest most corrupt cop" and the police chief "did nothing about it and covered up for this dirty cop."
The attorney general's office said it was unable to comment on pending litigation.