Prosecutorial Investigation Rights Reform (2019–2020)

Introduction

The 2019–2020 prosecutorial investigation rights litigation was a defining legal and political battle in South Korea, centering on the prosecution’s traditional power to direct criminal investigations. The dispute involved the Act on the Investigation of Corruption Crimes and the Establishment of the Corruption Investigation Office (CIO Act) , amendments to the Criminal Procedure Code limiting prosecutorial investigation authority, and multiple constitutional complaints challenging these reforms. The controversy reflected deep tensions between prosecutorial independence and democratic accountability.

Background

Under the Korean criminal justice system, the prosecution has historically held investigative primacy: prosecutors could direct police investigations, conduct their own investigations, and decide whether to indict. This power made the prosecution one of the most powerful institutions in South Korea.

Moon Jae-in Administration Reform

The Moon Jae-in administration (2017–2022) made prosecutorial reform a centerpiece policy. Key legislative changes included:

• Criminal Procedure Code Amendment (2019): Limited prosecutors’ direct investigative authority to certain categories (corruption, economic crimes, election crimes, etc.)
• Establishment of CIO Act (2020): Created an independent Corruption Investigation Office for High-ranking Officials (CIO), removing high-level corruption investigations from the prosecution

Legal Challenges

Constitutional Complaints by Prosecutors

Prosecutors and the prosecution service filed constitutional complaints challenging:

• The restriction of prosecutorial investigative authority (2019Hun-Ma1160, etc.)
• The establishment of the CIO as infringing prosecutorial independence

Prosecutors’ Arguments

• Principle of prosecutorial independence: The prosecution’s investigative authority is constitutionally guaranteed under Article 12(3) (warrant requirement implicitly recognizing prosecutorial investigation)
• Separation of powers: The legislature cannot restructure investigative authority in ways that undermine the prosecution’s constitutional role
• Equal protection: The CIO targets only high-ranking officials, creating unequal treatment

Government and Reform Supporters’ Arguments

• Legislative discretion: The National Assembly has broad authority to structure criminal procedure
• Accountability: The prosecution’s historical abuse of investigative authority necessitated reform
• Comparative practice: Most democracies separate investigation from prosecution

Constitutional Court Decisions

2019Hun-Ma1160 (Partial Rejection)

In a 2020 decision, the Constitutional Court largely upheld the Criminal Procedure Code amendments, holding that:

• The prosecution’s investigative authority is not constitutionally guaranteed in its traditional form
• The legislature may restructure investigative authority to enhance checks and balances
• The reforms did not violate the principle of separation of powers

CIO Establishment Upheld

The Constitutional Court also upheld the CIO Act, finding that the establishment of an independent anti-corruption body for high-ranking officials was within legislative competence and did not unconstitutionally infringe prosecutorial authority.

Consequences

Implementation

The reforms took effect in stages during 2020–2021:

• The CIO began operations in January 2021
• Police gained primary investigative authority over most offenses
• Prosecutors retained authority to request additional investigations from police

Political Fallout

The prosecutorial reform deepened conflict between the Moon administration and the prosecution service. The subsequent Yoon Suk-yeol administration (2022–present), led by a former Prosecutor General, has signaled a more prosecution-friendly approach, though the core reforms remain in place.

Conclusion

The prosecutorial investigation rights litigation represents a pivotal moment in South Korean criminal justice reform. The Constitutional Court’s validation of legislative power to restructure investigative authority has fundamentally altered the balance between prosecution and police, creating a more pluralistic investigative system while maintaining constitutional accountability.