• Continuing, for 18 days, to be Trump's national security adviser despite warnings from the top Justice Department official at the time, Sally Yates, that the Russians knew Flynn was lying about his conversations and, thus, had leverage over him.
• Was the person Trump pressured then-FBI Director James Comey to lay off investigating, according to Comey's notes. (Flynn "is a good guy," Comey recalled the president as saying to him.)
But perhaps the most damning of all of Flynn's troubles — and the one that could keep haunting the Trump administration — is something that has little to do with Russia: Flynn was working for the Turkish government while working for Trump, which means that he was advocating for policies that benefited Turkey while serving as Trump's national security adviser. And Trump may have known about this.
Those revelations are from reports late Wednesday published by McClatchy and The New York Times. Taken together, they're damning because what Flynn did gets at the heart of being a democracy: He was on the payroll of a foreign government while in a powerful position in the U.S. government.
Lobbying for a foreign government while simultaneously working for the U.S. government crosses just about every ethical red line you can think of, according to experts.
Texas Gov. Greg Abbott, R, just fired a top state official because the official didn't tell Abbott that he was also working for the Iraqi government. When that happened, I talked to Meredith McGehee with the Campaign Legal Center about why such dual roles are a fireable offense. She explained:
"There's recognition that there are competing interests and a number of potential conflicts that arise between one government and a foreign government," McGehee said. "That's just kind of built into a system, where a public servant is supposed to be serving the American people, not serving a second master."
She added: "Can you imagine a U.S. senator saying, 'Oh, yeah, I'm a U.S. senator and, at the same time, I'm lobbying on behalf of Mexico'"?
As for how this ties to Trump, The New York Times reports that Flynn told the president's transition team weeks before the inauguration that the Justice Department was looking into his undisclosed lobbying for Turkey. So it's very possible that Trump knew Flynn had financial ties to the Turkish government when the president hired Flynn as his top adviser on national security.
As McClatchy reports, the potential conflicts involving Flynn started almost immediately. He wrote an opinion piece for the Hill on Election Day titled "Our ally Turkey is in crisis and needs our support."
And, as McClatchy reports, the Turkish-U.S. Business Council moved its annual summit from the Ritz-Carlton to the Trump International Hotel in Washington.
The United States has a law — the Foreign Agent Registration Act — to prevent this sort of conflict. It says U.S. citizens who lobby for foreign governments have to tell the Justice Department about it. Flynn didn't do that. He didn't disclose his lobbying work to the federal government, nor to Trump (at least immediately). Flynn, as a former military official, also has to get the military's permission to do this kind of lobbying work.
"The notion you would be working for any government entity and also lobbying on behalf of a foreign government is quite concerning," McGehee said.
For all of the above, Flynn is at the center of a myriad investigations.