Why is it so hard to arrest an impeached president?

There were more than 100 police officers and they were armed with a warrant – but the South Korean authorities failed to arrest ousted President Yoon Suk Yeol after six hours of deadlock in front of his house.

That's how the confrontation with Yun's security team went on, as they formed a human wall and used vehicles to block the arrest team's path, according to local media.

It's been an unprecedented month for South Korean politics, with Yun's shocking but short-lived martial law order followed by a vote to impeach him. Then came the criminal investigation, his refusal to appear for questioning and, earlier this week, a warrant for his arrest.

The right-wing leader still has a strong support – and thousands of them turned up outside his home on Friday morning to oppose his arrest.

But by many accounts, Yun is now a disgraced leader – removed from parliament and removed from office, awaiting the decision of the constitutional court, which could remove him from office.

So why did it prove so difficult for the police to arrest him?

Although Yun was stripped of his presidential powers – after lawmakers voted to impeach him – he is still entitled to a security detail.

And those men played a key role in blocking Friday's arrest.

The Presidential Security Service (PSS) may have acted out of loyalty to Yun or out of “a misunderstanding of their legal and constitutional role,” said Mason Ritchie, an associate professor at Hankuk University of Foreign Studies in Seoul.

With Yoon suspended, the PSS must take direction from acting president Choi Sang-mok. “They have either not been instructed by Acting President Choi to step down, or they are refusing his orders to do so,” said Assoc. Richie.

Some experts believe that security officials have shown “unconditional loyalty” to Yun, rather than to the office itself. They point to the fact that PSS chief Park Jong-joon was appointed to the post by Yoon last September.

“It may be that Yun has saturated the organization with hard-line loyalists in preparation for just that possibility,” said US-based lawyer and Korea expert Christopher Jumin Lee.

And that Park's predecessor was former Defense Minister Kim Yong-hyun, who is accused of advising Yun to impose martial law. He is currently being held for questioning as part of the criminal investigation against Yoon.

The “simplest” solution, Mr Lee says, is for acting President Choi to order the PSS to step down temporarily.

“If he is unwilling to do so, it may be grounds for his own impeachment by the National Assembly,” he added.

Choi, who is finance minister, stepped in to lead the country after lawmakers voted to impeach Yun's first successor, Prime Minister Han Duk-soo.

This political impasse also reflects the polarization in South Korean politics – between those who support Yun and his decision to impose martial law, and those who oppose him. And the differences don't necessarily end there.

The majority of South Koreans agree that Yun's declaration of martial law on Dec. 3 was wrong and that he should be held accountable, says Duyeon Kim, assistant senior fellow at the Center for a New American Security — but they can't to agree on what accountability looks like.

“Participants disagree about the process, the procedure and their legal basis, which contributes to the current political uncertainty,” she explains.

That uncertainty has also created tense standoffs like the one that played out Friday in and outside Yun's presidential residence, where his supporters have camped out for days, leading to heated speeches and even clashes with police.

Law enforcement could return with more agents and use force, but that would be “very dangerous,” said Assoc. Mason.

The PSS is also heavily armed, so arresting officers will seek to avoid escalation.

“What will happen if the police show up with additional warrants calling for the arrest of PSS officials, (the PSS) also defy those warrants and then brandish their weapons?” asks Mr Lee.

Police have already said they are investigating the PSS director and his deputy for obstruction – so more charges and arrest warrants could be forthcoming.

The fallout from Yoon's martial law order is also a challenge for the Corruption Investigation Office (CIO), which is investigating him.

It has only been in operation for four years. It was created in response to public anger against former President Park Geun-hye, who was impeached, removed from office and later imprisoned in a corruption scandal.

While South Korean presidents have been jailed before, Yoon was the first to face arrest before stepping down.

Investigators have until Jan. 6 to arrest Yoon before the current warrant expires.

They may try to arrest Yoon again over the weekend, although the weekend could pose more of a challenge if the crowds of supporters swell. They can also seek a new order and try to detain him again.

Given how far South Korea has slipped into uncharted territory, uncertainty is likely to continue.

Additional reporting by Ewe Koh