According to Fredie Didier, the principles of Civil Procedural Law are due process of law, human dignity, legality, adversarial proceedings, full defense, publicity, reasonable duration of proceedings, equality, efficiency, good faith, effectiveness, adequacy, cooperation, respect for the self-regulation of will in the process, primacy of the decision on the merits, and protection of legitimate expectations.
Phew! It seems like a long list, but unraveling the principles of Civil Procedural Law is about understanding the "rules of the game." It involves understanding how legal action, jurisdiction, and process work, but above all, it requires strategic knowledge when dealing with the most frequent demands in Brazilian courts.
So, let's unravel everything about the principles of Civil Procedural Law in an easy and quick way. Shall we?

Principle of due process of law
The purpose of this principle is to prevent the parties from being harmed by unspecified practices. Let's see:
"No one shall be deprived of liberty or property without due process of law," article 5, paragraph LIV of the Federal Constitution . This is, therefore, a fundamental legal principle that guarantees that procedural acts are carried out in accordance with current law.
Furthermore, the doctrine also divides this principle into formal due process (procedural guarantees) and substantive due process (which would be proportionality and reasonableness in the decisions themselves).
Read also: GENERAL THEORY OF APPEALS IN CIVIL LAW
Principle of the dignity of the human person
Let's now move on to the second principle of Civil Procedural Law. In addition to Article 1, item III, of the Federal Constitution (CF), Article 8 of the Code of Civil Procedure (CPC) stipulates that the adjudicating body must "safeguard and promote" the dignity of the human person in Brazilian civil proceedings.
Here, human dignity is understood as a right of complex content, composed of all fundamental rights (those provided for in the Federal Constitution and inherent to the human person).
Principle of legality (juridicality)
Article 8 of the Brazilian Code of Civil Procedure establishes that the adjudicating body must observe the principle of legality in Brazilian civil procedure.
"In applying the legal system, the judge shall consider the social purposes and the requirements of the common good, safeguarding and promoting the dignity of the human person and observing proportionality, reasonableness, legality, publicity, and efficiency."
Thus, this principle of Civil Procedural Law seeks to prevent decisions based on natural law or law invented by the jurisdictional body, and instead, to establish law based on legislation.
Principle of adversarial proceedings and full right to defense.
The parties are guaranteed participation in structuring the process and the consequent possibility of influencing the decision.
"Litigants in judicial or administrative proceedings, and defendants in general, are guaranteed the right to due process and full defense, with the means and resources inherent to it," item LV, article 5 of the Federal Constitution.
Thus, the principle of adversarial proceedings in Civil Procedural Law seeks to eliminate surprise decisions.
And the principle of broad defense can be said to be the substantial aspect of this adversarial process, the guarantee of being able to defend oneself against any question that arises during the Brazilian civil procedure.
Principle of publicity
This principle of Civil Procedural Law ensures the availability of process data, which is considered an essential tool, since the process is public (here, it is worth highlighting the two exceptions to publicity: except in defense of privacy and social interest).
"The law may only restrict the publicity of procedural acts when the defense of privacy or the social interest so requires" item LX, article 5 of the Federal Constitution.
Principle of reasonable duration of proceedings
This principle of Civil Procedural Law seeks a process free from undue delays.
Attention, reasonable duration should not be treated as a synonym for speed. Fredie Didier states that "There is no principle of speed. The process does not have to be fast/swift: the process must take the time necessary and appropriate to resolve the case submitted to the jurisdictional body."
Therefore, it is always good to note that a reasonable process duration aims to avoid undue delays, but not speed at any cost.
Principle of equality
This principle of Civil Procedure Law stipulates that the judicial body must provide equal treatment to the parties in a lawsuit.
Therefore, the rules should be applied equally to the defendant and the plaintiff, considering: the impartiality of the judge, equality of access to justice, reduction of inequalities, and, lastly, equality of access to information.
Principle of efficiency
This principle of Civil Procedural Law aims to achieve satisfactory resolution of the dispute in quantitative, qualitative, and probabilistic terms; that is, it seeks assertiveness in the choice of procedural means.
Principle of good faith
"Anyone who participates in the process in any way must act in good faith," art. 5, CPC.
This principle of Civil Procedural Law does not require subjective good faith (the intention of the procedural subject), but objective good faith (the standard of conduct). Therefore, it can be said that the function of the principle of good faith is to establish an ethical standard of conduct for the parties in civil proceedings.
Principle of effectiveness
This principle of Civil Procedural Law ensures that rights must not only be recognized but also enforced, that is, the right to enforcement, the right to execution.
Principle of adequacy
The principle of adequacy seeks accommodation in three dimensions: legislative (according to legal production), jurisdictional (allowing the jurisdictional body to adapt the procedure to the peculiarities of the case), and negotiational (procedure adapted by the parties themselves, through negotiation).
There are doctrines that understand it as stemming from the principle of effectiveness, as Marinoni states : “the understanding of this right depends on the adequacy of procedural technique based on the needs of substantive law. If effectiveness requires adequacy and adequacy must bring effectiveness, the truth is that the two concepts can be broken down to better explain the need for the technique to be adapted to different situations of substantive law.”
Principle of cooperation
"All parties involved in the process must cooperate with each other so that a fair and effective decision on the merits is obtained within a reasonable time," Article 6 of the CPC.
This principle of Civil Procedural Law defines how the process should be structured, articulating the procedural roles of the parties and the jurisdictional body, with the aim of cooperating, harmonizing and dialoguing the dispute.
Principle of respect for the self-regulation of will in the process
This principle of Civil Procedural Law is closely related to freedom, that is, it is related to private autonomy in civil proceedings.
Therefore, it aims to create a feasible procedural space in which the right to self-regulation can be enjoyed by the parties without unjustified or unreasonable restrictions.
Principle of the primacy of the decision on the merits
Article 4 of the CPC guarantees the right to a complete resolution on the merits.
This principle of Civil Procedure Law states that the judge must prioritize the decision on the merits, that is, do everything possible to ensure that it occurs.
Principle of protection of legitimate expectations
Here, this principle of Civil Procedural Law is closely related to legal certainty.
Ultimately, it aims to protect the trust of a particular party in the process. Thus, as Fredie Didier says, "the principle of legal certainty and the principle of trust are, therefore, facets that complement each other semantically: security is the general facet of trust; trust, the particular facet of security."

Final considerations on the principles of Civil Procedural Law
Understanding the principles of Civil Procedural Law will be essential, as it will give you the confidence to make effective arguments that respect the law and build authority in your name, especially in the area of Civil Procedural Law, a field that will likely be demanded by most of your firm's clients or by the parties in the court where you practice.
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