The idea of a sitting president being arrested, once deemed unthinkable, now looms as a real possibility in South Korea.

President Yoon Suk Yeol, who narrowly avoided impeachment Saturday, faces investigations from three of the nation’s major investigative agencies amid massive political backlash over his declaration of martial law last week. On Monday afternoon, the Ministry of Justice imposed a travel ban on President Yoon, making him the first sitting president in South Korean history to face such a measure.

Is all this pointing to Yoon’s possible arrest in the near future? How would such an unprecedented scenario unfold and what would it mean for the future of South Korea’s democracy?

Here’s a look.

Yoon’s arrest “legally” possible

South Korea has seen many former presidents arrested, but never a sitting president, as presidents are protected by criminal immunity during their term.

Article 84 of the Constitution states: "The president shall not be charged with a criminal offense during his tenure of office except for insurrection or treason."

The only presidents charged with treason -- Chun Doo-hwan and Roh Tae-woo who led a military coup as military generals -- were investigated years after they stepped down from the top post.

However, Yoon is being accused of insurgency while in office.

After the president's declaration of martial law on the night of Dec. 3, troops were sent to the National Election Commission and the National Assembly.

Though reasons for the former were unspecified at the time, the latter had the clearer purpose of preventing lawmakers from striking down the martial law with a vote. Both bodies have Constitutional independence from the government, meaning Yoon's actions could be deemed unconstitutional.

An arrest is possible for "any criminal suspect (who) commits crimes punishable with death penalty, imprisonment with labor for an indefinite term, or imprisonment, with or without labor, for not less than three years," and if the suspect is likely to destroy evidence, escape, or has already escaped, according to Article 200-3 of the Criminal Procedure Act. Punishments for the act of leading, participating in or commanding insurrection, under Article 87 of the Criminal Act, include death and imprisonment for life.

In short, an incumbent president suspected of insurrection can be arrested for investigation from a strictly legal standpoint.

What if Yoon resists?

Local experts point out that if Yoon refuses to submit to law enforcement, any attempts at forceful measures would likely be restricted in practice.

The Presidential Security Service is mandated to protect the leader of the country around the clock, while Yoon's authority as a sitting president remains intact.

The Ministry of National Defense reaffirmed Monday that Yoon is still the legal commander-in-chief, though his presidency may be in a "vegetative" state.

In February 2017, during the criminal investigation against corruption suspicions surrounding former President Park Geun-hye, police were blocked by the presidential security service from entering the compound -- despite having a court-issued search and seizure warrant for the presidential office. This standoff ultimately led to a compromise, with the presidential office handing over the requested data.

Park's presidential powers had been suspended at the time, due to parliament passing the motion for her impeachment. It was a month before the Constitutional Court confirmed her removal from office.

Yoon currently still has all the powers of the president -- even if the political situation prohibits him from actively exercising them -- leaving the prospect of his arrest murky.

What would happen after arrest?

Questions would remain even in the event of Yoon's arrest, as the Constitution does not stipulate procedures for when a president is detained for criminal investigation.

Article 71 of the Constitution states that if an office of presidency is vacated or the president is unable to perform their duties for any reason, the prime minister or the members of the State Council in the predetermined order set by law should act in their place.

In this case, Prime Minister Han Duck-soo would become the acting president.

However, the case of a president being in temporary custody for criminal investigation has never been contemplated before, meaning the “vacancy" clause could be up for debate should Yoon decide to challenge it.

In the most extreme scenario, we may even see a president attempting to govern from prison.