Article from The New York Times by Adam Liptak.

WASHINGTON — Like lots of Americans, Robert Frese is not shy about expressing his views on the internet. Last year, in a comment on a newspaper’s Facebook page, he said a New Hampshire police officer who had given him a traffic citation was “a dirty cop.” The police chief, Mr. Frese added, was a coward who had covered up the matter.

The police officers might have looked the other way. They might have responded, explaining their positions and letting readers decide who was right. They might have filed a civil suit for libel, seeking money from Mr. Frese.

Instead, they did a fourth thing, one that seems at odds with the American commitment to free expression, particularly where criticism of government officials is concerned. They arrested Mr. Frese, saying he had committed criminal libel.

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“The fundamental defect of criminal libel statutes is that they’re unconstitutionally vague,” he said. “The practical result of that is that police departments, like the police department in Exeter, get to choose when they want to go after speech that is arguably defamatory.”

Image Credit: By Jamelle Bouie [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons