In an interview on CNN with Chris Cuomo, the documentary filmmaker Michael Moore said (at 16:15):
“Our president is under a criminal investigation possibly for treason or treasonous activities with his compatriots,” Moore said.
“Our president [Trump] is under a criminal investigation possibly for treason or treasonous activities”
The crime of treason is defined by the US Constitution as:
Treason against the United States, shall consist only in levying war against them, or in adhering to their enemies, giving them aid and comfort.
As Politifact noted, the framers of the Constitution narrowly defined the crime of treason to avoid scenarios that would hamper freedom of expression.
On the most basic level, treason has to occur in wartime, or during an armed rebellion against the government. And with the possible exception of an American working against U.S. troops in a place like Afghanistan, “there is no treason occurring on any side now,” said Jed Shugerman, a legal historian at Fordham Law School.
Since Russia is not at war with the US, President Trump cannot be acting in a treasonous manner in his dealings with Russia as defined by law.
Politifact also noted that under common usage, “treasonous”, as opposed to “treason” can be applied to a range of behaviors that fall outside of the narrow legal definition. However, Moore appeared to be talking about the strict legal definition as he mentioned the “criminal investigation” of Trump and Russia.
We rate this claim False.