On Monday, National Security Advisor Michael Flynn resigned, causing a swirl of controversy to erupt surrounding his abrupt departure with voices on both sides calling for an investigation and many critics wondering if he possibly broke this one centuries old law. 

Gage Skidmore/Flickr - flic.kr

Flynn had inappropriate ties with Russia and wasn't upfront with the Trump administration about his knowledge with Russian officials, and as such, left himself vulnerable to black mail. This now makes two presidential administrations Flynn has left; in 2014, Flynn was essentially "forced out" of the Obama administration before his term ended due to "clashing" with high-ranking officials, The Washington Post reports. 

Were Flynn's ties to Russia a violation of the Logan Act?

The Logan Act is a federal law that was passed in 1799 under former President John Adams. It was enacted after George Logan, a Pennsylvania state legislator, tried to step in and negotiate peace between France and the United States on his own, without any direct orders to do so.

"Logan was successful in his goal — much to the disappointment of the leading Federalist party, which had been pushing for a war with France. So the party passed a law, named for Logan, meant to prevent any other U.S. citizens from involving themselves in foreign affairs without being authorized by the government," Mic reports. And whether or not Flynn broke this law is one of many questions being asked by the public.

Flynn noted in his resignation letter, which was obtained by CNN, that he inadvertently briefed the then Vice President-elect Mike Pence "with incomplete information" in regards to his phone correspondences with the Russian Ambassador:

"In the course of my duties as the incoming National Security Advisor, I held numerous phone calls with foreign counterparts, ministers, and ambassadors. These calls were to facilitate a smooth transition and begin to build the necessary relationships between the President, his advisors and foreign leaders. Such calls are standard practice in any transition of this magnitude.

Unfortunately, because of the fast pace of events, I inadvertently briefed the Vice President Elect and others with incomplete information regarding my phone calls with the Russian Ambassador. I have sincerely apologized to the President and the Vice President, and they have accepted my apology.

[...] I am tendering my resignation, honored to have served our nation and the American people in such a distinguished way."

What are some other questions raised by Flynn's resignation?

Now that Flynn has resigned, Twitter users began to wonder how deep Flynn's knowledge went of the situation, with senior CNN political analyst David Axelrod using a phrase made famous by the Watergate scandal, telling the media outlet, "What did the President know and when did he know it?"

Will Flynn be charged with breaking The Logan Act?

As of now, it does not appear likely that he will be charged for violating this law. However, Rep. Jason Chaffetz (R-Utah), chairman of the House Oversight Committee, says he's not pursuing an investigation into Flynn's Russian ties and, to quote Flynn, "inadvertent briefing" of "incomplete information," The Huffington Post reports. 

There's one other point to consider regarding the Logan Act - though it exists, it's never been used.  "No one has ever been found guilty of violating [The Logan Act]. It seems its main purpose these past 200 years has been as a political weapon for the opposition party to cast doubt on the other party's foreign policies," according to The Washington Post.

On Tuesday, Republican Senators called for an investigation into Russia, in addition to seeking a testimony from Flynn.

"I think everybody needs that investigation to happen," Sen. Roy Blun​t (R-Mo.), member of the Senate Intelligence Committee, said to KTRS radio Tuesday. "And the Senate Intelligence Committee, again that I serve on, has been given the principle responsibility to look into this, and I think that we should look into it exhaustively so that at the end of this process, nobody wonders whether there was a stone left unturned, and shouldn't reach conclusions before you have the information that you need to have to make those conclusions."