Yoon's trial on rebellion charges opens in South Korea. Here's what to know

SEOUL, South Korea — Yoon Suk Yeol's legal saga is far from over.

Ten days after he was ousted from office over his martial law declaration, the former conservative South Korean president appeared for the first time at his criminal trial Monday on high-stakes rebellion charges.

Yoon's decision to declare military rule and send troops to Seoul streets in December made him the country's first president to be indicted while in office. If convicted of rebellion, he could face a life sentence, or theoretically, the death penalty.

Here is what to know about the trial, which could take as long as two to three years:

Will Yoon be convicted of rebellion?

When the Constitutional Court upheld the parliament's impeachment of Yoon and removed him from office, it stated Yoon's violation of the constitution and other laws was too grave to be tolerated and ''betrayed public confidence." It said Yoon's martial law enactment ''caused confusion in the society, economy, politics, diplomacy and all other areas.''

Given the ruling, there is ''a low possibility'' for the criminal court to issue a different verdict so Yoon will likely be convicted on rebellion charges, said Park SungBae, a lawyer who specializes in criminal law.

Yoon has denied the rebellion charges brought by prosecutors in January. Yoon maintained his decree was a desperate yet peaceful attempt to raise public awareness about how the ''anti-state'' liberal opposition was allegedly abusing its legislative majority to obstruct his agenda and complicate state affairs.

''The fact that they built a rebellion charge over an event that lasted only a few hours and was resolved non-violently after the National Assembly's demand to lift the measures was immediately accepted … doesn't align with proper legal reasoning,'' Yoon said Monday at the court, according to Yonhap news agency.

Some observers earlier said Yoon's rebellion charges were debatable as his decree didn't lead to major violence or cause any serious civilian casualties.

What are the central issues?

The main issue in Yoon's criminal trial is whether his deployment of hundreds of troops to the National Assembly and election commission offices constituted an illegal attempt to shut down those institutions.

Yoon has defended his actions, saying he never attempted to paralyze the National Assembly and had always planned to accept the outcome if lawmakers voted to lift martial law — which they did just hours after its declaration. His claims contradict the testimonies of some military commanders, who say Yoon ordered them to drag lawmakers out of the chamber to prevent them from voting against his decree.

The Seoul court will focus on ''determining whether there was an intent to undermine constitutional order, and individually assess a broad range of specific actions, including the circumstances under which the military and police forces were deployed,'' said Yang Hong-seok, a lawyer.

What can a fresh election bring?

Yoon's dismissal prompted a June 3 snap election to choose his successor, who will be given a full five-year term.

Observes say Yoon will likely influence his People Power Party's selection of its presidential candidate, as he would want someone who can stand up for him and pardon him if he's convicted.

Yoon no longer enjoys presidential immunity from most criminal prosecutions. Experts say prosecutors could subsequently charge him with abuse of power and other crimes related to his martial law decree.

Park said Yoon's trial at the Seoul district court is expected to last one-two years as there are too many witnesses to question and too many documents to examine. Yang said he expects a verdict within a year, given how crucial the case is.