A commenter asks, apropos the Sedition Act post, what the common law of seditious libel was. Here’s what Sir William Blackstone’s immensely influential Commentaries on the Laws of England (published 1765-69) said, though note that there was controversy in early republican America as to (1) whether this was an accurate statement of historical English law, (2) whether in any event this law survived the shift to a republican form of government, and (3) whether the federal government (as opposed to state governments) could prosecute common law crimes without express statutory authorization:
[Libels], taken in their largest and most extensive sense, signify any writings, pictures, or the like, of an immoral or illegal tendency; but, in the sense under which we are now to consider them, are malicious defamations of any person, and especially a magistrate, made public by either printing, writing, signs, or pictures, in order to provoke him to wrath, or expose him to public hatred, contempt, and ridicule.
The direct tendency of these libels is the breach of the public peace, by stirring up the objects of them to revenge, and perhaps to bloodshed. The communication of a libel to any one person is a publication in the eye of the law: and therefore the sending an abusive private letter to a man is as much a libel as if it were openly printed, for it equally tends to a breach of the peace.
For the same reason it is immaterial with respect to the essence of a libel, whether the matter of it be true or false; since the provocation, and not the falsity, is the thing to be punished criminally: though, doubtless, the falsehood of it may aggravate it