Former President Carter is at it again. He’s meeting with leaders across the Middle East, and trying to shape policy.
If memory serves, the Logan Act is still on the books:
Any citizen of the United States, wherever he may be, who, without authority of the United States, directly or indirectly commences or carries on any correspondence or intercourse with any foreign government or any officer or agent thereof, with intent to influence the measures or conduct of any foreign government or of any officer or agent thereof, in relation to any disputes or controversies with the United States, or to defeat the measures of the United States, shall be fined under this title or imprisoned not more than three years, or both.
To be sure, the act has not been enforced since 1803. Henry Adams made a mildly tongue in cheek reference to it in his History of the United States. Adams noted that in 1803 the law, passed in 1799, "still stood on the statute book (as it did in 1889 when Adams published his chef d’oeuvre.
Even so, the principle is important. In a constitutional republic such as our’s, the federal government is the sole rightful authority in foreign affairs.