Seoul, South Korea - A South Korean judge sentenced former President Yoon Suk Yeol on Friday to five years in prison for obstructing justice and other crimes linked to his disastrous martial law declaration and in its chaotic aftermath.

It is the first in a series of verdicts for the disgraced ex-leader, whose brief suspension of civilian rule in South Korea on December 3, 2024, prompted massive protests and a showdown in parliament.

Now ousted from power, he faces multiple trials for actions taken during that debacle and in the turmoil that followed.

On Friday, Judge Baek Dae-hyun at Seoul's Central District Court said he found Yoon guilty of obstruction of justice by blocking investigators from detaining him.

Yoon was also found guilty of excluding cabinet members from a martial law planning meeting.

"Despite having a duty, above all others, to uphold the Constitution and observe the rule of law as president, the defendant instead displayed an attitude that disregarded the... Constitution," Baek said.

"The defendant's culpability is extremely grave," he said.

But Yoon was not guilty of forging official documents due to lack of evidence, the judge said.

Yoon has seven days to appeal, he added.

Prosecutors had called for a 10-year prison term, while Yoon had insisted no law was broken.

The decision comes days after prosecutors in a separate case demanded Yoon be sentenced to death for his role as the "ringleader of an insurrection" in orchestrating the imposition of martial law.

They argued Yoon deserved the severest possible punishment as he had shown "no remorse" for actions that threatened "constitutional order and democracy."

If he is found guilty, it is highly unlikely the sentence will actually be carried out, as South Korea has had an unofficial moratorium on executions since 1997.

Yoon was seen smiling in court as the prosecutors demanded the punishment.

The former leader and top prosecutor has remained defiant, saying his martial law declaration was a lawful exercise of his presidential authority.

In closing remarks on Tuesday, he insisted the "exercise of a president's constitutional emergency powers to protect the nation and uphold the constitutional order cannot be deemed an act of insurrection."

Yoon accused the then-opposition party of having imposed an "unconstitutional dictatorship" through their control of the legislature.

"There was no other option but to awaken the people, who are the sovereign."

The court is scheduled to rule on the insurrection charges on February 19.

Yoon also faces a separate trial on charges of aiding the enemy, over allegations he ordered drone flights over North Korea to bolster his case for declaring martial law.