Jarrett is correct. No one has ever been prosecuted under it, and in addition to the Sixth Amendment issues brought up in the 1964 case, there are indeed significant First Amendment issues as well.
The Supreme Court has repeatedly outlined that criminal statutes cannot have vague and undefined terms that do not put citizens on notice as to what conduct is prohibited.
To satisfy due process, a penal statute [must] define the criminal offense [1] with sufficient definiteness that ordinary people can understand what conduct is prohibited and [2] in a manner that does not encourage arbitrary and discriminatory enforcement. Kolender v. Lawson, 461 U. S. 352 (1983).
The Logan Act, as written fails the vagueness test. It doesn’t take a legal scholar to see why. That’s the point the Court in 1964 made.
In addition, first amendment jurisprudence has radically changed what was in place in 1799. The Logan act targets speech based on content. Content restrictions are subject to strict scrutiny. It is extraordinarily difficult for any governmental regulation that targets the content of speech to survive strict scrutiny.
Only those regulations that are absolutely necessary and narrowly tailored (with the least restrictive means possible) to achieve a compelling governmental interest can survive such scrutiny. In fact, in the entire history of First Amendment jurisprudence, on only two occasions has a content based regulation survived Supreme Court review on a First Amendment challenge.
The Logan act is breathtakingly broad in scope and is certainly not the least restrictive means that its stated goals could be accomplished.
So yes, it probably violates the First Amendment in addition to the Sixth.
Thank you for your excellent comments on the subject.
Great opinions on Logan Act