Prosecutorial Reform Phase 2 Reignites Debate Over Supplementary Investigation Powers

Social media debate has intensified as the Prosecutorial Reform Task Force under the Prime Minister's Office pushes ahead with second-phase legislation on prosecutorial reform.

The central issue is whether to retain prosecutors' "supplementary investigation powers"—their authority to conduct additional investigations when evidence or facts are insufficient in cases transferred from police. The government aims to finalize amendments to the Criminal Procedure Act, including provisions on supplementary investigation powers, by the first half of the year following extensive public deliberation. Implementation is targeted for October 2, coinciding with the launch of the Public Prosecution Agency and the Serious Crimes Investigation Agency.

An analysis by Seoul Economic Daily using big data analytics platform "SomeTrend" found that mentions of "prosecutorial reform" on social media surged from under 400 daily through March 4 to 1,806 on March 6. References to "supplementary investigation powers" jumped from around 100 to 308 over the same period. Analysts attribute the spike to the government task force's March 6 announcement initiating public consultation on the second-phase legislation.

"The first-phase legislation is now in the hands of the party and the National Assembly, and the government will proceed with preparing follow-up legislation without delay," Noh Hye-won, deputy head of the Prosecutorial Reform Task Force, said at a briefing at the Government Complex Seoul on March 6. "Follow-up legislation will focus on institutional improvements necessary for smooth criminal proceedings after separating investigation and prosecution functions, including abolishing supplementary investigation powers, determining exceptional needs, and establishing practical and effective mechanisms for requesting supplementary investigations."

Under the Criminal Procedure Act, supplementary investigation powers allow prosecutors to directly conduct additional investigations into cases transferred by police, including compulsory measures such as warrant requests and arrests or detentions. However, calls to abolish these powers have grown louder, particularly from the ruling party. Critics argue that retaining them would undermine the core principle of prosecutorial reform: separating investigation from prosecution.

Additional concerns include potential abuse of investigative authority, preservation of prosecutorial staffing levels, and the risk that successive administrations might attempt to expand these powers. On February 5, the ruling party's general assembly adopted as official party position a proposal to grant prosecutors only the right to "request supplementary investigations" while abolishing their direct investigation powers.

Opponents of abolition argue it could directly harm the public by eliminating opportunities to correct police investigative failures. They cite cases where prosecutorial supplementary investigations identified the true perpetrator in a child sexual abuse case in Tongyeong, South Gyeongsang Province, and overturned a police decision not to prosecute in a sexual assault case involving a person with intellectual disabilities in Jangheung, South Jeolla Province.

President Lee Jae-myung has acknowledged the need to retain supplementary investigation powers in exceptional circumstances. "I believe prosecutors should not conduct supplementary investigations," Lee said at a January press conference. "But if a case is transferred with only two days remaining on the statute of limitations, a complete ban on supplementary investigations would mean the remaining time expires while the case shuttles between police and prosecutors."

"The approach should be to block possibilities of abuse, create safeguards for truly exceptional cases, and then permit such measures to efficiently handle government affairs," Lee added.

An analysis of negative keywords associated with "supplementary investigation powers" on social media from March 2-6 reveals divided opinion. Terms related to abolition concerns—"side effects" and "worries"—appeared 47 and 38 times respectively. Keywords associated with retaining prosecutorial investigation powers—"abuse" and "coercion"—registered 31 and 26 mentions.

The government has emphasized that second-phase legislation, including the question of retaining supplementary investigation powers, will undergo sufficient social discussion and public deliberation. "As with the first phase, we plan to systematically conduct public consultation in coordination with the party," Noh said. "From next week through mid-April, we will hold up to 10 discussion sessions with relevant organizations including the Korean Bar Association, Citizens' Coalition for Economic Justice, and criminal law academic societies. We will also convene forums in regional areas including Gwangju, not just the Seoul metropolitan area, to gather diverse local opinions."