Although at first view it can seem a matter without importance, since the only proof with the capacity to disprove the presumption of innocence of the accused is the one practiced during a public trial, the declaration of the accused plays an important role during the beginning of the judicial process.
The first thing we have to take into account is the possibility to investigate the suspect without its knowledge according to the article 302 of the Spanish Penal Procedural Law (in Spanish Ley de Enjuiciamiento Criminal, henceforth LECrim), this is to avoid that the suspect meddles with the investigation because its interference could result in the destruction of proofs. Notwithstanding the law obliges the Instructor Judge to lift the secret of summary ten days before it ends.
Another thing we need to know is that the only mandatory proof is the LECrim is the declaration of the suspect, we can see it reflected in the article 385 for the ordinary procedure and also the article 775 for the abbreviated procedure. So if we now mix the two we already know logically at least ten days before the end of the summary the Instructor Judge has to take declaration to the suspect. But here is when arrive the polemic. Though the LECrim includes the declaration of the suspect as a diligence some judges or tribunals have interpreted it as a guarantee, the difference is really important, because it opens the door to whole investigation at the back of the suspect. In other words, if we consider the declaration of the suspect as a guarantee the Instructor Judge can carry out an investigation and conclude it, without the participation of the suspect. And he can comply with this requirement of the law once the investigation is finished as a formality.
But let see this last point more carefully, because we have two possibilities. The Instructor judge may have informed the suspect of the investigation but have not took to him declaration, then consider this declaration as a guarantee and through this comply with the law and continue with the procedure once the summary has ended. Or the other possibility is when the Instructor Judge has not informed of the investigation to the suspect, and once it has ended take to him declaration. In the later case we are violating the right of defense of the suspect, who has the right to know of the investigation since it is open against him and participate in it (art. 311 LECrim), at least it is declared secret under article 302, and notwithstanding this case as we have seen above he has the right to know about it 10 days before the conclusion of the summary. In the former case, how is considered this diligence is not important since we are complying with the law in the moment we put into the knowledge of the suspect the existence of the investigation.
We can be even more concrete. The suspect has the right to know about the investigation carry out against him since the report (art. 269 LECrim) or lawsuit is admitted (art. 313 LECrim) by the Instructor judge or the police has concluded its report and has shared it with the Instructor Judge who has approved it. Here I see a sort of conflict between the stablished in the LECrim to the ordinary procedure and the abbreviated procedure, because while the article 118 guarantees the right to defense during the abbreviated procedure, this right is also guaranteed by the article 384 in the ordinary procedure. We can find the reason in the difference between these two procedures because, while in the ordinary procedure we have an “auto de procesamiento” a resolution necessary to take declaration to the accused and to inform him of his defense rights, in the abbreviated procedure we have the article 118 to inform the suspect of his defense rights and the articule 775 as mandatory before the process can continue to the intermediate phase. In the abbreviate procedure we have the “auto de transformación a procedimiento abreviado”, which can be a sort of equivalent to the “auto de procesamiento” in the ordinary procedure. In other words, article 118 applies to both procedures, which means that in the ordinary procedure the defense rights of the investigated are guaranteed two times.
Now I am going to contradict myself. I have said at the onset of this writing that the only proof with the capacity to destroy the presumption of innocence of the accused is the proof practiced in a public trial. But here also the casuistic is diverse. We can see a suspect who has confessed the crime during the summary or investigation but once in the trial he decides to exercised his right to guard silence, in this case, if the declarations where he admitted the crime were taken with all the guarantees (in front of the Instructor judge and in the presence of his lawyer) the tribunal can use this declarations to sentence him as guilty, because these declarations may be introduced according to art. 714, it means reading during the trial the act which took the declaration. If the declaration where the suspect confessed the crime was not taken with all the guarantees as may happen in a declaration only taken in front of the police, this never can serve as a proof valid in a trial, not even using the art. 714, to destroy the presumption of innocence of the accused. When we talk about a confession of a crime during the summary is important to recall the art. 406, which has been interpreted by the tribunals giving whole validity to the confession when there are other proofs of the crime, while when there are more proofs of the crime aside the confession the Instructor Judge is oblige to continue investigating until it finds others proofs to support the accusation during the trial. The important is that we have to take into account that a confession during the summary can serve as a proof during the trial if it is supported by other proofs, even when during the trial the accused decides to make use of his right to not declare.
To close this writing, I want to stress that is important to follow what is stated by the law, and take declaration to the suspect before the summary is ended to really guarantee his right to defense, and that we have to be careful with what we said during the instruction, because it can also be used against us during the trial.