헌법상 무기대등원칙의 실질화와 형사증거법의 과제 -사인이 수집한 증거의 ‘준증거화’ 방안을 중심으로-

This article analyzes the challenges of criminal evidence law from the perspective of substantively realizing the constitutional principle of equality of arms, focusing on the Quasi-Evidence Theory, which reconceptualizes materials collected by private investigators as a new evidentiary category. The current criminal justice system is structurally unbalanced due to the State’s monopoly over evidence formation, resulting in a fundamental infringement of the defendant’s procedural self-determination derived from Article 10 of the Constitution. To address this imbalance, the article proposes redefining lawful fact-finding activities conducted by private investigators as quasi-public procedural acts and institutionalizing their outputs as Quasi-Evidence. This framework is constitutionally grounded in Roxin’s Principle of Responsibility and Tribe’s Process Value Theory, while the probative value of investigative materials is controlled through a Standard for Procedural Reliability Review. Furthermore, drawing on Kelsen’s Grundnorm theory, the article clarifies the normative status of the Quasi-Evidence Theory and presents concrete legislative proposals, including the introduction of a Public Defender Investigator System and Article 318-4 of the Criminal Procedure Act. Ultimately, this study presents the Quasi-Evidence Theory as a practical model for transforming the criminal justice paradigm into a new constitutional order in which procedural equality is substantively achieved.