A (Im)Possibilidade de Utilização de Provas Ilícitas no Processo Penal Brasileiro: Limites e Exceções à Luz da Teoria do Fruto da Árvore Envenenada e da Proporcionalidade

This paper proposes a thorough reflection on the issue of illegally obtained evidence in Brazilian criminal procedure, based on legal doctrine and case law. The Federal Constitution enshrines the inadmissibility of evidence obtained through illicit means, a principle that permeates the entire procedural criminal legal framework. The study addresses the general theory of evidence and the importance of its production within the boundaries of due process of law, ensuring compliance with the principles of adversarial proceedings, full defense, and the presumption of innocence. It then examines the “fruit of the poisonous tree” doctrine, as well as the exceptions recognized by legal scholarship and jurisprudence, such as the independent source doctrine, the inevitable discovery rule, and the exceptional application of proportionality in favor of the defense. Through a methodology based on bibliographic research, employing scientific articles, doctrinal books, legislation, and case law on the subject, the study seeks to outline the path toward understanding the fruit of the poisonous tree doctrine and the principle of proportionality. Furthermore, it highlights the need to strengthen oversight mechanisms of police and prosecutorial activities, ensuring the effective accountability of agents who produce or validate illegal evidence, and to guarantee civil reparations for victims of state abuse. The conclusion suggests that, in order to ensure the integrity of criminal proceedings, jurisprudence must remain strict in evaluating the legality of evidence, especially in cases involving home entries, wiretapping, or searches in the context of drug trafficking and other serious crimes.