You knew this was coming. This morning President Trump tweeted about John Kerry’s shadow diplomacy to preserve the Iran deal:

The Boston Globe reported Friday that Kerry has been quietly making calls to members of Congress and sitting down with foreign leaders, including Iran’s Javad Zarif, urging them to keep the Iran deal in place. And Kerry isn’t operating alone. Former Energy Secretary Ernest Moniz and a group of Obama-era State Department officials are backing his effort.

A short time after Trump’s tweet, a spokesman for John Kerry issued a response:

“Secretary Kerry stays in touch with his former counterparts around the world just like every previous Secretary of State,” the statement reads. But Kerry is lobbying for a specific outcome on a specific issue and doing so contrary to the stated preference of the President of the United States. That may not be illegal but it’s a lot more than keeping in touch with old friends.

Trump’s reference to this effort being “possibly illegal” is a reference to the Logan Act, a 200-year-old law which says Americans may not negotiate foreign policy without approval from the government. No one has ever been successfully prosecuted under the Logan Act, and there’s a good argument to be made that it violates the First Amendment. So the chance that Kerry is going to prison for a Logan Act violation is beyond slim.

But the left’s interest (or disinterest) in the Logan Act is situational. Back in 2015 when Sen. Tom Cotton and 46 other Senators signed a letter to Iran about the Iran deal, some suggested it was a violation of the Logan Act. More significantly, it was the Logan Act which apparently initially concerned AG Sally Yates (an Obama holdover) about a conversation Michael Flynn had with Russian Ambassador Sergey Kislyak. From the Washington Post:

Yates, then the deputy attorney general, considered Flynn’s comments in the intercepted call to be “highly significant” and “potentially illegal,” according to an official familiar with her thinking.

Yates and other intelligence officials suspected that Flynn could be in violation of an obscure U.S. statute known as the Logan Act, which bars U.S. citizens from interfering in diplomatic disputes with another country.

At the same time, Yates and other law enforcement officials knew there was little chance of bringing against Flynn a case related to the Logan Act, a statute that has never been used in a prosecution. In addition to the legal and political hurdles, Yates and other officials were aware of an FBI investigation looking at possible contacts between Trump associates and Russia, which now included the Flynn-Kislyak communications.

Word of the calls leaked out on Jan. 12 in an op-ed by Post columnist David Ignatius. “What did Flynn say, and did it undercut U.S. sanctions?” Ignatius wrote, citing the Logan Act.

Finally, here’s Logan Act scholar Keith Olbermann in February, 2017 demanding an investigation into Flynn and Trump over possible Logan Act violations.