Mr Trump reportedly knew for at least three weeks that Michael Flynn, his former national security adviser, called the Russian ambassador to the US last year to reassure them that sanctions would be overturned. He was forced to resign this week.
Mr Flynn was interviewed by the FBI shortly after Mr Trump took office. The alleged misinformation he provided to intelligence agencies could be pursued in court, similar to the case of former General James Cartwright, who made false statements to FBI agents about cyberattacks on Iran’s nuclear programme and who was pardoned by former President Barack Obama.
Norm Eisen, former ethics lawyer for Mr Obama, said that if Mr Flynn did lie to the FBI he wold be prosecuted.
“We have seen this movie before: he will then roll over on Trump and others. It won’t be pretty,” he wrote on Twitter.
Mr Trump’s aides and associates allegedly had frequent and repeated communication with Russian members of government and intelligence in the run-up to the election, according to travel, bank and phone records obtained by US intelligence and law enforcement agencies.
This discovery raises questions over Mr Trump’s denial that he has ties to Russia.
Press Secretary Sean Spicer told reporters on Tuesday that he was not aware that any Trump aides had spoken to Russia during the campaign – but he was clear that Mr Flynn had spoken to the Russian ambassador after the election.
He insisted Mr Flynn was fired due to an “erosion of trust”, not because there was a legal issue.
The US intelligence agencies did not identify the aides involved or say how much of the communications related to business, rather than politics. They also did not conclude that the communication was evidence of the Trump team colliding with Russians to influence the election, but were concerned that Mr Trump had openly praised Vladimir Putin at the same time that Russian operatives were allegedly hacking the Democratic National Committee servers.
“Congress must act now or talk of Reagan winning the Cold War will be a sad joke,” warned Richard Painter, a former ethics counsel to George W. Bush.
If it were proved that the President's aides or associates did work with Russia to sabotage Hillary Clinton’s chances, spread fake news and hack DNC computers, it could violate the 1799 Logan Act, a statute that bars private citizens from interfering with diplomatic relations between the US and foreign governments.
It is not clear whether then President-elect Trump knew about Mr Flynn’s calls to Russia. If he did, he was a private citizen at the time. The caveat is that the Logan Act is essentially defunct and only two people, including a farmer from Kentucky, have been indicted under the law - in 1803 and 1852 respectively.
Jennifer Laurin, a professor at the School of Law in Texas, told The Independent that for Mr Flynn to be charged under the Logan Act, it would have to be proved that he communicated with Russian officials with the intent to influence the measures of the Russian government.
“Lawyers would have to prove he had intent to influence the Russian government’s conduct in some way,” she said.
“It would not be enough for him to simply communicate with Russians as a private citizen, or even that he was communicating with Russian intelligence officials.”
Laurence Tribe, a Harvard law professor, argued on Twitter that the latest revelations about Russia contributed to building the case for the President’s impeachment.
“Flynn’s departure from [the National Security Council] was necessary but far from sufficient,” he added.
“Bumping [chief strategist Steve] Bannon from his legally dubious role there must follow. Then investigating what POTUS [Mr Trump] knew and when he knew it; then considering whether POTUS is ‘unable to discharge the duties of his office’ within the meaning of Section 4 of the 25th Amendment; then starting a serious national conversation about possible impeachment.”
Ms Laurin added there was not enough evidence for impeachment to be considered.
“It remains an open and hotly contested question whether a sitting President can be criminally prosecuted,” she said.
“The closest lawyers came to that was in the proceedings of Richard Nixon, but the court never decided the question.”
Attorney General Jeff Sessions and Mr Flynn both sat on the Trump campaign’s National Security Council during the 2016 election.
Given the use of the Logan Act as a vehicle for rhetoric by the Tea Party during Mr Obama’s presidency, the odds are stacked against Mr Trump and his staff being prosecuted. Lawyers have also reportedly raised concerns around the Logan Act in terms of free speech and the right of the First Amendment.
Mr Tribe said he was “angered, saddened and disgusted” by the number of potential ethical violations around the President, which resulted in people not being able to focus on one at a time.
Several lawyers have already filed a suit challenging Mr Trump’s alleged use of the White House as a “personal and family profit centre”, according to Mr Tribe, and in allegedly doing so Mr Trump has violated the Constitution’s Emoluments Clause.
The Department of Justice has 60 days to reply to the complaint, and a case schedule will then be negotiated.
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