Illegal evidence as a normative gap and jurisprudential challenge in Peru

Abstract

This study analyzes the concept of illegal evidence and demonstrates the lack of normative and jurisprudential uniformity in how judicial actors assess such evidence within criminal proceedings. Although the Peruvian Constitution and the Criminal Procedure Code establish general guidelines for the exclusion of evidence obtained in violation of fundamental rights, no solid regulatory framework exists that provides precise criteria or specific exceptions. The methodology employed was dogmatic-legal, with a descriptive scope, a qualitative approach, and a non-experimental design. A case study was conducted, focusing on the analysis of constitutional and judicial rulings. The results show that the decisions of judicial operators are contradictory, which undermines legal certainty and equality before the law. In addition, relevant legal doctrines were examined, including the fruit of the poisonous tree doctrine, balancing, and proportionality—all of which guide the admission or exclusion of illegally obtained evidence depending on the degree of infringement upon fundamental rights. Finally, it is concluded that the jurisprudence of the Constitutional Court has evolved toward a flexible model. Through the introduction of the proportionality test and the theory of risk, the Court permits the admission of certain illegally obtained evidence in cases involving serious crimes or corruption. In such scenarios, public interest and the protection of state sovereignty take precedence over procedural formality.