The burden of proof, a fundamental institute of Procedural Law, consists of the charge assigned to the parties to demonstrate the veracity of the facts alleged in court, functioning simultaneously as an instruction rule for the parties and a judgment rule for the magistrate, whose primary purpose is to enable jurisdictional provision in situations of factual uncertainty.
1. Definition, Concept, and Legal Nature
The burden of proof (onus probandi) is qualified, from the perspective of general procedural theory, as an imperative of one's own interest. It differs from an "obligation" and a "duty" in that it does not entail a direct sanction or an enforcement claim in case of non-compliance; rather, failure to observe the procedural burden leads to a position of legal disadvantage, embodied in the risk of an unfavorable judgment.
The legal nature of the institute is twofold. As an instruction rule, it guides the behavior of the parties regarding which facts they must prove to support their claims. As a judgment rule (or closure rule), it is intended for the magistrate, serving as a subsidiary criterion to decide the dispute when the evidence produced is insufficient or non-existent, avoiding non liquet (refusal to judge due to lack of clarity).
Doctrinally, James Goldschmidt's theory is a reference point in treating the burden as a "legal situation" of the need to act to avoid prejudice, moving away from the idea of a duty toward the State or the opposing party.
2. Historical Evolution and Comparative Law
The genesis of the institute dates back to Roman Law, synthesized in the maxims "ei incumbit probatio qui dicit, non qui negat" (the proof lies with the one who affirms, not the one who denies) and "reus in exceptione fit actor" (the defendant, when raising an exception, becomes the plaintiff). In the classical Romano-Germanic system, the rigidity of static distribution prevailed, where the plaintiff proved the constitutive fact and the defendant the impeditives, modificatives, or extinctive facts.
In the contemporary scenario, there is a transition from a rigid model to a model of dynamic distribution. Countries such as Argentina (through the doctrine of Jorge Peyrano) and Germany influenced the flexibilization of the burden, allowing the judge to assign the charge to the party that holds better technical, economic, or informational conditions to produce the evidence. In Brazil, this evolution culminated in the express codification of the principle of dynamization in the 2015 Code of Civil Procedure.
3. Legal Provision and Normative Framework
The Brazilian legal system regulates the burden of proof in various statutes, adapting it to the specificities of each branch of Law:
- Code of Civil Procedure (CPC/2015): Art. 373 establishes the static rule in the caput (I - plaintiff; II - defendant) and the dynamic rule in §1, allowing for judicial redistribution in light of the peculiarities of the case or excessive difficulty in fulfilling the charge.
- Consolidation of Labor Laws (CLT): With the Labor Reform (Law 13.467/2017), Art. 818 began to mirror the CPC system, expressly providing for dynamic distribution in labor proceedings.
- Consumer Defense Code (CDC): Art. 6, VIII, provides for the reversal of the burden of proof as a basic right of the consumer, conditioned on the plausibility of the allegation or technical/economic hypossufficiency.
- Code of Criminal Procedure (CPP): Art. 156 provides that the proof of an allegation shall be incumbent upon the one who makes it. However, under the prism of the Federal Constitution (Art. 5, LVII), the principle of presumption of innocence prevails, which imposes on the Public Prosecutor's Office the full burden of proving authorship and material evidence of the crime.
4. Practical Application and Consolidated Jurisprudence
The application of the burden of proof has been the subject of intense praetorian activity in the superior courts:
Superior Court of Justice (STJ)
The STJ has consolidated the understanding that the reversal of the burden of proof in the CDC is an instruction rule and not a judgment rule. This implies that the decision to reverse the burden should occur preferably during the case sanitization phase, allowing the burdened party to exercise the right to an adversarial proceeding (REsp 1.284.454/MS). Recently, in Repetitive Theme 1061, the STJ defined that, in lawsuits regarding bank contracts with allegations of fraud, it is up to the financial institution to bear the burden of proving the authenticity of signatures and the regularity of transactions.
Superior Labor Court (TST)
In the labor sphere, jurisprudence is peaceful regarding the burden of proof for overtime. TST Precedent 338 establishes that it is the employer's burden, if they have more than 20 employees, to record working hours. The unjustified failure to present time records creates a relative presumption of the veracity of the hours indicated by the employee.
Supreme Federal Court (STF)
In criminal proceedings, the STF reinforces that the prosecution's burden of proof is non-delegable. The court has ruled that the reversal of the burden of proof to the detriment of the defendant is incompatible with the Democratic State of Law, even in tax crimes or money laundering cases, where proof of the legality of assets cannot be demanded from the accused in an absolute manner without prior proof of the underlying illicit act.
5. Related Principles and Doctrinal Divergences
The institute dialogues with fundamental principles:
- Principle of Cooperation: The magistrate must signal in advance the intention to redistribute the burden to avoid surprise decisions.
- Principle of Equality of Arms: Dynamization seeks to balance procedural forces, avoiding the requirement of probatio diabolica (impossible proof).
A relevant doctrinal divergence lies in the nature of the reversal of the burden in the CDC: whether ope legis (by force of law, e.g., Art. 12, §3) or ope judicis (by judicial decision, e.g., Art. 6, VIII). The majority doctrine and STJ jurisprudence strictly distinguish both, applying distinct requirements for each hypothesis.
6. Contemporary Relevance and Practical Impacts
The modernization of the burden of proof is essential in the digital age. The difficulty of producing evidence in algorithmic or artificial intelligence environments has led jurists to defend the application of the dynamic burden theory to hold data-holding companies accountable. The practical impact is the reduction of impunity and greater effectiveness of jurisdictional protection, as the process ceases to be a game of formalities to become an instrument for the search for possible procedural truth.
Legal and Jurisprudential References
- BRAZIL. Law No. 13.105, of March 16, 2015. Code of Civil Procedure.
- BRAZIL. Law No. 8.078, of September 11, 1990. Consumer Defense Code.
- BRAZIL. Decree-Law No. 5.452, of May 1, 1943. Consolidation of Labor Laws.
- STJ. Precedent 297: The Consumer Defense Code is applicable to financial institutions.
- STJ. Repetitive Theme 1061 (REsp 1.846.649).
- TST. Precedent 338: Working Hours. Registration. Burden of Proof.
