President Trump on Thursday accused former secretary of state John F. Kerry of violating the Logan Act, a relatively obscure and seldom-enforced centuries-old law that prohibits private citizens from conducting diplomacy.

There are two reasons that’s potentially problematic.

The first is because Trump suggested he had run the idea up the flagpole.

“I’d like [Iran] to call me,” Trump said. “You know, John F. Kerry speaks to them a lot. John F. Kerry tells them not to call. That’s a violation of the Logan Act. And frankly, he should be prosecuted on that. But my people don’t want to do anything that’s — only the Democrats do that kind of thing.”

Trump trailed off when he started to talk about what his “people” thought of the idea of prosecuting Kerry, making it sound as if he had broached the topic with somebody. That’s important, because it suggests he may have floated the idea of prosecuting yet another of his political adversaries.

Exactly whom Trump may have discussed this with would be of interest. Just last week, Attorney General William P. Barr struggled with a question from Sen. Kamala D. Harris (D-Calif.) about whether Trump or the White House had requested any specific investigations.

Here’s the exchange. Barr took a long pause after the first question:

HARRIS: Attorney General Barr, has the president or anyone at the White House ever asked or suggested that you open an investigation of anyone?

BARR: I wouldn’t — I wouldn’t ...

HARRIS: Yes or no?

BARR: Could you repeat that question?

HARRIS: I will repeat it. Has the president or anyone at the White House ever asked or suggested that you open an investigation of anyone? Yes or no, please, sir.

BARR: The president or anybody else?

HARRIS: Seems you'd remember something like that and be able to tell us.

BARR: Yes, but I’m trying to grapple with the word “suggest.” I mean, there have been discussion of, of matters out there that they’ve not asked me open an investigation, but ...

HARRIS: Perhaps they've suggested?

BARR: I don’t know. I wouldn’t say suggest.

HARRIS: Hinted?

BARR: I don't know.

HARRIS: Inferred? You don’t know. Okay.

And here’s the video:

Trump never said he proposed the idea to Barr or anyone else specifically, but it’s worth asking who might have been involved in such conversations. And as we saw in the Mueller report, Trump hasn’t always been terribly careful about overstepping the boundaries between the presidency and the Justice Department when it come to political allies and adversaries.

The second reason is that it brings the whole Michael Flynn situation rushing back — and suggests Trump has pulled a 180 on the application and importance of the Logan Act.

The Logan Act says you can’t contact foreign governments or their representatives “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.”

Flynn was discovered to have discussed sanctions with Russia’s ambassador shortly after the Obama administration announced them — during the transition period between Trump’s election and inauguration — urging Russia not to retaliate. Flynn got in trouble not for violating that law, though, but for lying about his conversations to investigators.

Still, at the time, Trump seemed largely unconcerned with the idea of his incoming national security adviser conducting diplomacy even though he was a private citizen at the time. When asked about whether it bothered him that Flynn had discussed sanctions, Trump said: “It certainly would have been okay with me if he did it. I would have directed him to do it if I thought he wasn’t doing it.”

He added: “General Flynn obviously was dealing. . . . But he was dealing as he should have been.”

Trump might argue that it was okay for Flynn to do such things, since he was an incoming official in the U.S. government, but the law makes no distinction on that count. It refers to private citizens, which both Flynn and Kerry were.

Last, it’s worth emphasizing that the case Trump lays out against Kerry is highly suspect. There is no evidence that Kerry is asking Iran not to conduct diplomatic talks with the Trump administration. And in the past, Trump has suggested it might be a Logan Act violation simply for Kerry to talk to Iran.

A Kerry spokesman responded Thursday: