Security was tight in Seoul on Friday morning ahead of the Constitutional court's ruling on the impeachment of South Korean President Park Geun-hye.
Police said it had mobilised about 4,600 officers around the court. The Seoul Metropolitan Police Agency on Thursday put its forces on high alert and deployed thousands of officers and hundreds of buses in the streets surrounding the court. South Korean protesters supporting and opposing Park held separate rallies before the ruling on the impeachment in front of the Constitutional Court.
Park was impeached by parliament in December and stripped of her powers pending the court's ruling. If the court strikes down the impeachment, Park will be reinstated.
The ruling starts at 0200gmt and it will be televised live, court spokesman Bae Bo-yoon told reporters. He declined to comment on whether the judges had already reached a conclusion.
Park is accused of violating her constitutional duty by colluding with a friend, Choi Soon-sil, to pressure big businesses into making contributions to foundations set up to support her policy and allowing her to exert influence on state affairs.
Park has apologised for putting trust in Choi, but denies any legal wrongdoing.
Close to a million South Koreans would rejoice if anti-Park rallies in the past month are to go by.
For Park to be formally removed, at least six of the court's eight justices will have to support the impeachment motion filed by lawmakers, which accuses the president of extortion, bribery, abuse of power and leaking government secrets.
If the court unseats Park, the country's election law requires a presidential vote within 60 days, which likely means May 9.
The ruling would instantly strip Park of her powers and also her immunity against prosecution. She could be interrogated by prosecutors seeking to indict her on criminal charges after repeatedly refusing to be interviewed by prosecutors over the scandal in past months.
If a presidential election is triggered, opinion polls favour liberal opposition politician Moon Jae-in, who lost the 2012 race to Park, to succeed her.
A Moon presidency could bring significant changes after a decade of conservative rule. He stresses the need for dialogue with belligerent, nuclear-armed North Korea, which would be a dramatic departure from Park's hard line.
Moon also vows to "reconsider" the South's plans to deploy this year an advanced US anti-missile system; China says the system's powerful radar is a security threat.
If Park makes a comeback
The court restoring Park's powers would be a victory for tens of thousands of her conservative supporters who rallied passionately near the court in recent weeks.
It would also vindicate party loyalists who stuck with her even as dozens of their colleagues defected to create a new party in anticipation of an early presidential election. Such a decision will likely take the air out of the investigation into the scandal.
What does this mean for the next elections?
Some experts believe Park's reinstatement would only delay for a few months what seems to be an inevitable liberal presidential victory.
Park's single five-year term was originally due to end in February 2018, and regardless of the court's ruling, her credibility may be hopelessly compromised, the experts say.
That's not ideal when she must navigate the country amid growing North Korean threats, a bad economy that could get worse with the diplomatic dispute with China, and a public sharply divided over the nation's future.
Some experts worry that Park's reinstatement could trigger a violent reaction from the millions of protesters who have been occupying the streets of major cities nationwide in the past several months.
The anti-Park rallies have been mostly peaceful, but some protesters said their "candles will turn into torches" if the court refuses to uphold Park's impeachment.
If Park returns to office, the country's next presidential election will be held on December 20 as originally scheduled.