A few states retain archaic statutes making some types of libel a crime. They're rarely used. They show up fairly regularly in stupid legal threats, and very occasionally in politically motivated harassment prosecutions.
Minnesota's statute criminalizes statements that "expose a person or a group, class or association to hatred, contempt, ridicule, degradation or disgrace in society, or injury to business or occupation." It offers a defense of justification for a few exceptions:
Violation of subdivision 2 is justified if:
(1) the defamatory matter is true and is communicated with good motives and for justifiable ends; or
(2) the communication is absolutely privileged; or
(3) the communication consists of fair comment made in good faith with respect to persons participating in matters of public concern; or
(4) the communication consists of a fair and true report or a fair summary of any judicial, legislative or other public or official proceedings; or
(5) the communication is between persons each having an interest or duty with respect to the subject matter of the communication and is made with intent to further such interest or duty.
Isanti County prosecuted Timothy Robert Turner for violation of this statute when he posted malicious ads on Craigslist in the name of his ex-girlfriend and her daughter soliciting strangers for sex. He added their cell phone numbers. Timothy Robert Turner is scum.
The Minnesota Court of Appeals agreed that Turner's actions were contemptible and defamatory. But they found that the statute violates the First Amendment. First, it doesn't recognize that truth is an absolute defense to defamation — under the statute, you could be criminally prosecuted for making a true statement without "good motives." Second, it criminally punishes false statements about public figures or matters of public concern without requiring the government to show that the statements were made with actual malice — the long-standing standard protecting such speech.
Notice that the loathsome Timothy Robert Turner's speech was unquestionably false, and wasn't uttered about public figures or matters of public concern. But the Court overturned the statute in his case and reversed his conviction anyway. Why? In First Amendment cases, when a statute is so defective that it prohibits a substantial amount of constitutionally protected speech, courts will allow a litigant to challenge the entire statute even if the particular litigant's speech could constitutionally be punished. That's sometimes called the overbreadth doctrine. Here, the state conceded that the statute was overbroad (and possibly even conceded that it's substantially overbroad — it's hard to tell). The state asked the court to employ a remedy in this situation — to construe the statute narrowly to make it constitutional, that is, to say "Minnesota can only use this statute in cases involving false statements, and only by proving actual malice in cases involving public figures or matters of public interest." Courts are supposed to do that when they reasonably can rather than strike down an entire statute. Here, the court not unreasonably found that they'd have to fundamentally rewrite the statute to save it, and refused to do so. The line between narrowly construing a statute to save it and "rewriting" a statute is not perfectly clear.
The bottom line: the Minnesota court recognized that an archaic criminal libel statute was invalid when it didn't include the free speech protections afforded modern civil defamation defendants.
Eugene Volokh submitted a clearly effective amicus brief. Timothy Robert Turner escapes conviction, but hopefully never gets a job or relationship again thanks to Google.