Legitimacy, a fundamental institute of Procedural and Constitutional Law, embodies the subjective pertinence of an action, establishing the necessary link between the subjects of the legal relationship and the object of the litigation, serving as an indispensable condition for the regular exercise of the right of action and the delivery of jurisdictional relief.
Concept and Foundation
Legitimacy, as a condition of an action, translates the authorization granted by the legal system for a specific subject to appear as a plaintiff or defendant in a procedural relationship. In classical doctrine, legitimacy is defined as the "subjective pertinence of the action." It is not enough to hold the substantive right; it is imperative that the plaintiff and the defendant occupy the appropriate procedural positions, according to the theory of assertion, whereby the conditions of the action must be assessed in light of the allegations made by the plaintiff in their initial petition.
From a civil procedural perspective, the legal nature of legitimacy is a matter of public order, cognizable ex officio by the magistrate at any time and degree of jurisdiction, pursuant to Art. 485, § 3, of the Code of Civil Procedure (CPC/2015). The absence of legitimacy — legitimatio ad causam — results in the dismissal of the case without resolution of the merits.
Origin and Historical Evolution
The evolution of the concept of legitimacy goes hand in hand with the overcoming of the immanentist theories of Roman Law, which confused the right of action with the substantive right itself. The autonomization of the action, initiated by the famous controversy between Windscheid and Muther (1856), allowed legitimacy to be treated as an autonomous requirement. In Brazilian Law, the transition from the 1939 Code system to the 1973 Code and, subsequently, to the current 2015 CPC, consolidated legitimacy as an integral element of the interest-legitimacy binomial, abandoning the old classification of "legal possibility of the request" as an autonomous condition of the action, absorbing it into the merits of the case.
Legal Provision and Normative Structure
The Brazilian legal system establishes legitimacy as a prerequisite for procedural validity:
- Code of Civil Procedure (Art. 17): "To postulate in court, it is necessary to have interest and legitimacy."
- Code of Civil Procedure (Art. 18): Enshrines the principle of procedural substitution, prohibiting anyone from pleading the right of another in their own name, unless authorized by the legal system.
- Federal Constitution (Art. 5, XXXV): The foundation of access to justice, which presupposes legitimacy as a filter for the system's rationality.
Practical Application and Current Jurisprudence
The consolidated understanding of the Superior Court of Justice (STJ) adopts the theory of assertion. According to REsp 1.879.467/SP, the legitimacy of the parties is verified according to the factual narrative presented in the initial pleading, without the need for deep evidentiary proceedings, under penalty of prematurely entering into the merits. Within the scope of the Supreme Federal Court (STF), legitimacy gains specific contours in the concentrated control of constitutionality (Art. 103 of the CF/88), restricting the list of those legitimized to propose ADI, ADC, ADO, and ADPF, conferring the nature of "extraordinary legitimacy" to the entities listed therein.
Related Principles and Divergences
Legitimacy is intrinsically related to the principle of the inalienability of jurisdiction and the principle of due process (adversarial system). Doctrinal divergences persist regarding the nature of legitimacy in necessary joinder of parties (litisconsórcio), where the integration of all subjects as defendants is an imperative for the effectiveness of the judgment. The majority view argues that, in cases of extraordinary legitimacy, the legitimized party acts as a procedural substitute, acting in their own name to defend the interest of another, a fundamental distinction for the application of res judicata.
Contemporary Relevance
In contemporary times, the debate on legitimacy has expanded to Collective Law. The STF, in recent rulings (such as Theme 1170 of General Repercussion), discusses the limits of the legitimacy of associations to propose public civil actions, reinforcing the need for express authorization or specific statutory provision. The practical impact is direct: the correct assessment of legitimacy avoids wasting the judicial machinery and ensures legal certainty in procedural relationships, preventing parties unrelated to the conflict of interests from being subjected to the effects of a judicial ruling.
Legal and Jurisprudential References
- BRAZIL. Law No. 13.105, of March 16, 2015. Code of Civil Procedure.
- BRAZIL. Constitution of the Federative Republic of Brazil of 1988.
- STJ. REsp 1.879.467/SP, Rapporteur Min. Nancy Andrighi, Third Panel, judged on 10/06/2020.
- STF. ADI 7005, Rapporteur Min. Luís Roberto Barroso, Plenary Court, recent decision on the legitimacy of associations.
- MARINONI, Luiz Guilherme; ARENHART, Sérgio Cruz; MITIDIERO, Daniel. Course on Civil Procedure. Vol. 1. São Paulo: RT.
