Understanding the Criminal Trial Process and Rules of Evidence

The Criminal Trial Stage

The trial is the stage of legal proceedings where the defendant's conduct is prosecuted to either convict or acquit, culminating in a sentence that ends the process. It is conducted in one or more sessions and develops under several key principles. Once the trial opens, it continues for as many consecutive sessions as necessary for its completion.

Governing Principles of a Trial

The procedural debate is governed by the following principles:

• Orality: Proceedings are conducted verbally.
• Publicity: The trial is open to the public, ensuring transparency.
• Concentration: The trial proceeds through consecutive sessions without undue interruption.
• Contradiction: Both parties have the right to contest evidence and arguments.
• Equality: The prosecution and defense are given equal opportunities.

The conduct being judged is precisely that which has been the subject of the prosecution; therefore, other facts cannot be prosecuted. The adversarial principle of contradiction necessitates that this phase begins with a provisional qualification letter, which formally lays out the charge, determines the facts to be tried, and requests the imposition of a penalty. This principle also gives the defendant the opportunity to object to the classification and penalties being applied or to comply with them.

Publicity and Exceptions

The trial must be developed under the principle of public disclosure, with any violation risking nullity. However, a trial may be held in camera (privately) if the court resolves that it is necessary for the protection of a specific right. The publicity of the trial should operate without restrictions, and secrecy is the exception, applied only for reasons of public order or the protection of rights and freedoms.

Rules and Types of Evidence

Early or Pre-Trial Evidence

Early testing is necessary for evidence that, for various reasons, cannot be presented during the actual trial. This designation applies to evidence proposed in the qualification writings after the trial has opened, particularly when it cannot be presented with other evidence while respecting the principles of contradiction, immediacy, orality, and publicity.

Illegally Obtained Evidence

A judge must exclude illegally obtained evidence under elementary rules of exclusion. Evidence that has been obtained unlawfully cannot be validly used in criminal proceedings. The truth cannot be reached at any cost; evidence obtained directly or indirectly by violating fundamental rights and freedoms shall have no effect.

If the offense affects the substance of a fundamental right, there is no doubt that the evidence is worthless, has no legal effect, and must be excluded. For example, if a defendant has testified under torture, that incriminating statement clearly cannot be used to convict them.

The Doctrine of the Poisonous Tree

Under the doctrine of the "fruits of the poisonous tree," if the principal evidence is obtained illegally, any subsequent evidence derived from it is also considered contaminated and inadmissible.

Types of Admissible Evidence

Expert Evidence

Expert evidence involves reports issued to the judicial authority by individuals with specialized knowledge in a particular field. These experts analyze the facts presented by the court and offer their professional opinions on them.

Documentary Evidence

In certain cases and investigations, documentary evidence is necessary. This includes using documents as proof, such as in cases involving written slander, libel, or business disputes.