The in dubio pro reo principle, of a guarantor nature, constitutes a fundamental pillar of Criminal Procedural Law and Constitutional Law. Its primary purpose is to ensure that evidentiary uncertainty regarding the authorship or materiality of a crime results in the acquittal of the accused, operating as a direct corollary of the presumption of innocence.
Concept and Foundation
The in dubio pro reo principle, also known as favor rei, embodies a rule of judgment and an ethical-legal imperative that prohibits the issuance of a conviction in the absence of absolute certainty regarding the criminal responsibility of the agent. Its legal nature is that of a protective norm, endowed with constitutional status, which imposes the burden of proof (onus probandi) on the State and establishes doubt as an impediment to punishment.
Historical Origin and Evolution
The genesis of the institute dates back to Roman Law, consolidating itself in the maxim favorabiliora sunt in dubio benigniora. Historically, the principle evolved from the inquisitorial logic — where doubt could lead to torture or conviction — to the modern adversarial paradigm. In contemporary constitutionalism, the principle is a direct development of the presumption of innocence (Art. 5, LVII, of the 1988 Federal Constitution), transmuting from an interpretive guideline into a subjective right of the accused not to be subjected to a sanction without full proof of culpability.
Legal and Constitutional Provision
Although not explicitly stated as a single provision, in dubio pro reo is extracted from the systematic exegesis of the legal order:
- Federal Constitution (CF/88), Art. 5, item LVII: "No one shall be considered guilty until the final and unappealable criminal conviction".
- Code of Criminal Procedure (CPP), Art. 386, item VII: "The judge shall acquit the defendant, mentioning the cause in the dispositive part, provided that they recognize there is insufficient evidence for a conviction".
- International Treaties: American Convention on Human Rights (Pact of San José, Costa Rica) (Art. 8, 2), which reinforces the presumption of innocence as a minimum guarantee.
Practical Application and Jurisprudence
The jurisprudence of the Superior Courts (STF and STJ) is unanimous in recognizing that doubt, in criminal proceedings, must work in favor of the accused. The consolidated understanding is that a conviction requires a judgment of certainty; probability or mere likelihood is not sufficient.
In recent rulings, the STF has reiterated that evidentiary fragility, especially in crimes against sexual dignity or in contexts of plea bargains lacking corroboration, mandates acquittal. The STJ, in turn, has crystallized the understanding that the existence of isolated circumstantial elements, without support in evidence produced in court under the scrutiny of the adversarial system, is insufficient to prevent the application of in dubio pro reo.
Related Principles and Divergences
In dubio pro reo is frequently contrasted with the in dubio pro societate principle. However, the majority doctrine and guarantor jurisprudence reject the application of in dubio pro societate at the sentencing stage, maintaining that such a concept is incompatible with the Democratic Rule of Law. The only doctrinal exception lies in the indictment phase of the Jury Tribunal, where part of the jurisprudence still admits in dubio pro societate, although the debate over its constitutionality is intense, with influential voices in the doctrine advocating for its total exclusion from the system.
Contemporary Relevance
In the current scenario of the expansion of Criminal Law and the use of new evidentiary technologies, the principle acts as a check on arbitrariness. Its contemporary relevance lies in protecting the individual against the "spectacle of criminal proceedings" and convictions based on the magistrate's subjective convictions, reaffirming that the process must be an instrument for the search for truth, not a means of legitimizing pre-judgments.
Legal and Jurisprudential References
- BRAZIL. Constitution of the Federative Republic of Brazil of 1988. Brasília, DF.
- BRAZIL. Decree-Law No. 3.689, of October 3, 1941. Code of Criminal Procedure.
- STF, HC 164.493/AM, Rapporteur Min. Gilmar Mendes, Second Panel, judged in 2020.
- STJ, AgRg in HC 734.567/SP, Rapporteur Min. Jesuíno Rissato (Summoned Judge), Fifth Panel, judged in 2023.
- LOPES JR., Aury. Direito Processual Penal (Criminal Procedural Law). 20th ed. São Paulo: Saraiva, 2023.
