South Korean police have beefed up security in areas around the court, preparing to deploy all forces from midnight into the ruling day on Friday.
The acting chief for the national police force, Lee Ho-young, said the area around the court would be turned into a “vacuum state” to restrict access and cordon off pro- and anti-Yoon rallies to prevent any potential clashes.
Vowing to act sternly against any violence, Lee said police will arrest those who vandalise facilities, threaten justices or assault police officers.
In January, hundreds of Yoon supporters stormed a court building after his detention was extended, smashing windows and breaking inside.
Han has directed police to step up security for constitutional court justices.
Amid deepening political strife, opposition parties brought a motion to impeach finance minister Choi Sang-mok in parliament on Wednesday.
Cho was the second acting president and had angered opposition parties that have a commanding majority in parliament by repeatedly vetoing bills and not appointing a Constitutional justice approved by the assembly.
The opposition parties are however likely to hold off voting on Choi’s impeachment bill before Yoon’s ruling.
Bracing for big rallies and a heavy police presence on the ruling day, foreign embassies have issued alerts calling for extra caution.
The United States embassy in Seoul said on Wednesday that it would cancel routine consular operations like visa interviews on the afternoon of Apr 3 and all day on Apr 4.
The Chinese embassy has told its nationals to stay away from large political protests and not to participate in those rallies.
