Third Section. The Expert´s Report (art. 723 – art. 725 LECrim):
A Judge must know on the laws, this should be his expertise, we cannot exige to him to be a expert in nuclear science, or in psychology, or even in ballistics, although sometimes a knowledge on these sciences and others may serve to him to find the person liable of a crime. For example, the psychology may help him to assess how reliable is the testimony of the victim of a crime, the ballistics to know whence a gun was shot, or the nuclear science to ascertain if was a human mistake what made the reactor to explode and what provoked the natural disaster. Then, how can he fill these gaps in his understanding of a subject when it is necessary to solve if an accused is guilty or not? In these cases, he is assisted by an Expert in such subject.
The intervention of the Expert takes place in two parts of the procedure. First during the investigation of the crime, where the Examining Magistrate will always appoint an Expert when this is necessary for knowing or appreciating some important fact or circumstance due to the special knowledge on a subject that is required (art. 456 of the Spanish Criminal Procedural Law, in Spanish Ley de Enjuiciamiento Criminal, henceforth LECrim). The report of the Expert is important in this part of the procedure because, it will help the Examining Magistrate to determine the possible authorship of a crime, to assess what evidences he has against a suspect, and finally to decide the convenience of dictating a committal for trial (art. 384 LECrim) against him, which is one of the most important decisions during the Criminal Procedure, since the committal for trial delimits those liable of the crime and the facts which form such crime, without both things a crime cannot be categorized according to one of the precepts of the Criminal Code (in Código Penal, henceforth CP). Moreover, without first being committed for trial a suspect cannot be prosecuted, because by means of this judicial decision he is informed of the facts which point at him as suspect, giving to him the opportunity of participating in the investigation (art. 311 LECrim), and in consequence of appointing a lawyer of his confidence. The right to appoint an Expert is shared by the Examining Magistrate with the parties of the process when the report is of imposible repetition during the oral trial, in these cases the private prosecution and the defendant will have the right to appoint an Expert at their expense (art. 471 LECrim), who may contradict by his report, the report of the Expert appointed by the Examining Magistrate, here we can mention as example the analysis of the drug found in the possession of the suspect when he was arrested by the police.
The Expert may intervene again in the procedure during the oral trial, but his intervention will be determined by the contestation of one of the parties to his report. If one the parties wants to impugn the report of one of the experts, it has to do it in its writing of provisional qualification of the crime (art. 650 LECrim), otherwise the report of the Expert will be considered by the Tribunal as a valid proof for destroying the presumption of innocence of the accused (art. 24.2 of the Spanish Constitution), without the necessity of its practice during the oral trial. Such absence of the Expert to the oral trial, would be an exception to the general rule which establishes that the only valid proofs for destroying the presumption of innocence of the accused are those which has been practiced during the oral trial according to the following rules: 1) The proof has to be practiced in front of the Tribunal trying the case, 2) All the proofs must be the object the contradiction by the parties of the process, 3) The proofs must be practiced during a public process, and 4) The contradiction of the proofs during the oral trial must be carried out orally. Regarding the content of the contestation to the Expert´s report the demands are feeble, the party impugning the report only will have to show its disconformity with it, for provoking the attendance at the oral trial of the Expert.
If the report of the Expert is impugned by any of the parties of the process, the Expert is obliged to assist to the oral trial for supporting his report, where he will be subjected to the questions of the parties (art. 724 LECrim), and although the LECrim guards silence regarding the faculty of the Tribunal of asking also questions to the Expert concerning his report, the Spanish jurisprudence has admitted this possibility based on two motives: 1) The art. 708 grants to the Tribunal the right to ask questions to the witnesses (including the accused) during the oral trial, and 2) The art. 483 LECrim expressly authorizes the Examining Magistrate to make questions to the Expert during his elaboration of the report. Nevertheless, insofar as the Tribunal must adopt a neutral position trying the case, the questions which it directs to the Expert cannot suppose a disguised inquisitive activity, this sort of questions are only allowed to the prosecution.
I have left to the end the question of what is the effect of the Expert´s report upon the final decision of the Tribunal, its sentence. Here we have to take into account what is said by the article 117.3 of the Spanish Constitution, the exercising of the legal authority, trying and making to execute the tried, corresponds exclusively to the Judges and Tribunal determined by the laws. To the above, we have to add that the Tribunal is free at the hour of assessing the proof (art. 741 LECrim), therefore the Expert´s report does not bind the Tribunal, it only instructs the latter on certain subject. Notwithstanding the above, a Tribunal has limits when it has to asses the proof, the express constitutional prohibition of arbitrariness aimed to the public powers (art. 9.3 of the Spanish Constitution), and some kind of guidelines that the Spanish jurisprudence has developed for the interpretation of the proof, it has to be in accordance with the rules of the healthy critic, which are constituted by the exigencies of the logic, the scientific knowledge, the maxims of experience, and the common sense.
Thus we can conclude that, the Expert´s report is elaborated during the phase of investigation of the crime to help the Examining Magistrate to obtain the evidences which tie a suspect with the its commission, or it can be also used by the parties to obtain evidences which sustain their claims. Later, if any of parties contests the Expert´s report, the Expert will have to attend to the oral trial for supporting his report, and for complying with the principles which has to surround the practice of a proof for destroying the presumption of innocence of an accused, mainly its practice during a public oral trial where the parties have the opportunity of contradicting the proof. The fundamental idea is that, the Expert´s report is aimed to help the Tribunal, but does not supplant it in its labor interpreting the proof, since it is a faculty only reserved to the Tribunals by the Spanish Constitution and the law.