Yoon Suk Yeol, the president of South Korea, who was impeached in December over his failed attempt to impose martial law, will learn on Friday whether he will be formally removed from office or returned to power, the nation’s top court said on Tuesday.

Suspense was building in South Korea as the country waited for the Constitutional Court to rule on Mr. Yoon’s fate. Mr. Yoon has been suspended from office since the National Assembly impeached him on Dec. 14. In South Korea, the Constitutional Court decides whether an impeached official is removed permanently from office or reinstated.

Removing Mr. Yoon would require the votes of six or more of the court’s eight justices; otherwise, he will return to office.​ The court’s decision, which cannot be appealed, is a critical moment in the political upheaval​ that Mr. Yoon unleashed when he declared martial law on Dec. 3.

If ​the court removes him, Mr. Yoon will become the second president in South Korean history to leave office through impeachment. (President Park Geun-hye was the first, in 2017.) The country will quickly shift gears toward a new election; a successor must be chosen within 60 days.

If he is reinstated, South Korea’s political crisis is likely to deepen. Mr. Yoon’s attempt to impose martial law angered millions of South Koreans. Even if reinstated, he will resume his presidential duties with his ability to govern considerably weakened.

Mr. Yoon was detained on Jan. 15 on insurrection charges, also connected to his ill-fated imposition of martial law. The suspense surrounding his future intensified after a Seoul court unexpectedly released him from jail on March 8, saying that his detention was procedurally flawed.