This photo shows the entrance of the Constitutional Court in Seoul, Feb. 26. Yonhap

The Constitutional Court ruled Thursday that acting President Choi Sang-mok's decision to withhold the appointment of a court justice last year is an unconstitutional act, infringing upon the right of the National Assembly.

But the court dismissed a request to confirm the appointment of the justice, saying there were no grounds to make such a decision.

In a unanimous decision, the court found that Choi's failure to appoint opposition-recommended Justice candidate Ma Eun-hyuk to the court in December that left the bench one justice short violated the National Assembly's right to elect a justice to the court.

Assembly Speaker Woo Won-shik had filed a competence dispute case against Choi, arguing the acting president's failure to appoint Ma violated the National Assembly's right.

"The non-appointment of Justice candidate Ma Eun-hyuk infringes upon the petitioner's right to compose the Constitutional Court through the election of a court justice as granted by the Constitution," the court said.

Under the decision, Choi will be legally obligated to appoint Ma, but the court's dismissal indicates that it has no authority to enforce Choi to proceed with the appointment.

The decision had been closely watched as Ma's potential appointment is expected to impact ongoing cases at the court, including the impeachment trial of President Yoon Suk Yeol.

Following the ruling, Choi's office said that it respects the court's decision but remained cautious about whether Choi would immediately proceed with appointing Ma.

"Choi is expected to carefully review the court's decision before making a decision," a finance ministry official said on the condition of anonymity.

Consent by six justices is necessary to uphold Yoon's impeachment by the National Assembly over his failed martial law bid.

On Dec. 31, Choi appointed two justices to the court but held off on Ma's appointment, citing the need for a bipartisan consensus.

Following the final arguments in Yoon's impeachment trial early this week, the court's eight justices have deliberated on the case and cast a vote behind closed doors. (Yonhap)