The  principle of legality, known by the Latin expression  ‘nullum crimen, nulla poena sine lege’ , which means that ‘there is no crime or punishment without a prior law defining the’, it is very important in the study of law. This principle is found in several constitutions and also in penal codes and other documents.

Through the law it is possible to create duties, rights and impediments, being individuals dependent on the law.  It can be said that this principle represents a guarantee for all citizens, provided by the constitutions, because through it, individuals will be protected by acts committed by the State and by other individuals. From there, there is a limitation on state power to interfere in the individual liberties and guarantees of the citizen. Thus, in general, everyone is allowed to carry out any type of activity, as long as it is not prohibited or is in the law.

Principle of legality and legal reserve

It is important not to confuse the principle of legality with that of the legal reserve. The legality principle not only defines or informs a law, but determines whether the regulation of a matter should be made through formal or written law. It refers to the law or amendment that regulates a situation. Thus, this principle is found in two forms in the constitutions: absolute legal reserve and relative legal reserve. About the second, the prisoner will not be punished, if there was not previously a written, strict and just law.

Origin of the Principle of Legality

With various attributions, the principle of legality arose during the Enlightenment, in the seventeenth to eighteenth centuries, despite having been cited within the Roman Law. Through the Enlightenment philosophers that principle became one of the most used in law schools.

It was in 1764 that Beccaria, inspired by Rousseau, Montesquieu and other philosophers, published a work by anonymous author called ‘Crimes and Punishments ‘, which defended the end of all the cruelties exercised during the period of the Inquisition, and the irregularities committed by the courts and also proposed that you create pre-established, correct, and fair laws that everyone had access to, so the magistrate could apply them and people would be aware of their rights and guarantees.

The principle of legality was affirmed after the French Revolution of 1789. It arises in response to the oppressive power of the Old Regime, rejecting the jurisdictional function as conceived in the idea of ​​time. The magistrate, an officer of the king, said the law, and the law issued by the king. The rejection of this idea was translated into the doctrine of those who believed that the judge should be the “mouth of the law” and of those who believed that the “law of the courts” should be rejected in the oblivion of medieval customs. At the time, the idea is affirmed that the law can not be interpreted therefore, if not in a rigid and literal way. The conception of the judge as a mere by means of the rule has survived until our days, losing the partisan and Jacobin meaning of the jurisdictional function, and establishing a universal meaning: the principle of legality today expresses a political option whereby freedom is limited. In the essential measure to guarantee peace.

Historically, strict limits have been imposed on the jurisdictional function, for the benefit of the legislator, representative of the people, who can not be harmed. Enlightenment’s confidence in man’s reason then becomes concrete when we think that the law, as a material translation of natural principles, is intrinsically correct, and that the certainty of the law of instruments must be maximum. Therefore, it is raised to the constitutional principle of the Fundamental Charter, and among the addressees is the legislator, who can not delegate in others his task (delegation), due to the ordinary law. And this law will be subject to the constitutional judge, who will put to the test the correspondence with the highest principles.

Therefore, legality aims to show us the rights and duties to make us live in a civilized way. Therefore, it is proposed as a need for a prior state of law that grants power (for example, the Chambers).

The second purpose adds that the administration and jurisdiction must exercise their powers in accordance with the contents prescribed by law. The administration is obliged not only to pursue the purposes determined by law ( legality-direction  ), but also to operate in accordance with the regulations themselves (  legality-guarantee  ) (for example, magistrates).

This concept is also defined by Paul Johann Anselm von Feuerbach, who introduced the  Bavarian Penal Code of 1813  .


The rule dictated by the substantive law, to satisfy the principle of legality, must guarantee a high level of typicity: this does not deprive it, in general, of the “character of concretion, while it is applied to a multiplicity of cases, while the The judge’s sentence represents the rule of the specific case, that is, of the individual case. The character of the concrete is missing in the rules that contain  general clauses., but in some aspects they constitute exceptions within the civil law system, having above all the function of offering rules of conduct to the parties for unexpected events and to adapt to the circumstances of the case the legal rules or the ones agreed in the contract, as well as The function of providing a textual basis to the judge to find in the system the rule that will be applied in case of lack of a specific rule or to correct an unfair result that could be achieved with the mere application of a specific rule. In this sense, as is well known, general clauses have often been described as “wind” or “lung” of the legal system. In both cases, however, the judge elaborates the rule of the concrete case applying the rule dictated by the substantive law “ .


In addition, the need to specify the norm can not go so far as to deny its typicity, under the pain of creating a true antinomy. In fact, he lamented that “the paths of legitimacy and legality (the first, the adaptation to concrete expectations, the second, compliance with abstract rules)” are spreading: without “taking root, filling”, the gap between legality and legitimacy. , we can expect a tragic development of the conflict between illegitimate legality and illegal legitimacy ”  .