George Logan, call your office. Normally we’re not big fans of the act named after an 18th- and 19th-century Pennsylvania pol that criminalizes private involvement in diplomacy. Yet we find ourselves thinking of Senator Logan in the wake of news that the richest man in the world is trying to trade away Free China in an effort to be able to continue manufacturing his electrically powered cars in Communist China.

Elon Musk used an interview in the Financial Times to make his “recommendation” to downgrade the only Chinese democracy to an “administrative zone” under the communists. He conceded the idea “probably won’t make everybody happy,” though he hoped Taiwan’s treatment by the mainland would be “more lenient” than Hong Kong’s. Teslas, many made at Shanghai, gained Chinese “tax exemptions” after the comments, the New York Post reports.

Mr. Musk’s proposal was “welcomed by Beijing” and  “slammed in Taipei,” CNN reports. China’s envoy to America hailed the suggestion for “peaceful unification and one country, two systems.” Democrats on Taiwan aver that their “freedom and democracy are not for sale.” A senior lawmaker says that Mr. Musk’s “solution” is “all about victim concessions.” Mr. Musk, meantime, has been recommending appeasement in Ukraine.

Mr. Musk is a talented fellow with many interests, including, even, the colonization of Mars. Yet what gives him the idea that he has a role to play in American diplomatic affairs? It could be the same impulse that in 1798 prompted Logan — a gentleman farmer, pamphleteer, dabbler in medicine, and Quaker pacifist —  to try his hand at foreign affairs. Concerned by a potential Franco-American war, he sailed to Paris to try to forge peace.

The meddlesome Logan returned with pacific pledges from France. Yet far from earning laurels, critics called him treasonous. Congress was enraged. It enacted the law bearing his name as “a curb on all future self-appointed spokesmen,” as Time puts it. Yet Logan couldn’t restrain himself. At a time of war with Britain in 1813 he wrote asking Jefferson to “engage” President Madison to advance “just and honorable proposals” for peace.

The Logan Act itself makes it a crime for American citizens, absent the okay of the government, to engage in “verbal or written correspondence or intercourse” with foreign governments in an effort to “influence the measures or conduct” of foreign countries, particularly “in relation to any disputes or controversies” with America. The law has rarely — almost never — been invoked in the intervening years.  

Even so, President Trump said State Secretary Kerry breached the act by speaking in a private capacity to Iranian officials. The FBI weighed suggesting charges under it for Mr. Trump’s ex-National Security Adviser, Lieutenant General Michael Flynn, based on his interactions with Russians. It looks like Mr. Musk, who “thinks he’s Henry Kissinger,” as Jack Shafer quips, could be skating on thin ice with his global diplomacy.

Mr. Musk “could have violated” the Logan Act, Newsweek reckons, citing an “unconfirmed report” that the tycoon “spoke directly” with President Putin before mooting his plan for appeasement in Ukraine. Logan did once concede to Jefferson that his 1813 peace drive might trigger the “obloquy of a few infuriated, or self interested individuals.” Our view is that it’s bad enough we have self-driving cars, but self-driving diplomacy?