On a Criminal Procedure there are two figures who sway all what happens during it, the Examining Magistrate and the Judge. Between them is shared all the power, the parties are endowed with some faculties by the Spanish Criminal Procedural Law (in Spanish Ley de Enjuiciamiento Criminal, henceforth LECrim), like the power of initiating the procedure by a report or a lawsuit (art. 308 LECrim), of proposing proofs during the phase of investigation (art. 311 LECrim), of being present during the practice of the proofs during the phase of investigation (art. 333 LECrim), of being the accusation (art. 650 LECrim), of proposing the proofs which will be practiced during the oral trial (art. 656 LECrim), of marking the boundaries which the sentence must respect (art. 732 LECrim), but any of these faculties cannot be compare with which is attributed by the LECrim to the two most important figures of the Criminal Procedure.
Let´s start from the beginning. The Criminal Procedure can be initiated by a citizen, to this it has two means, a report or a lawsuit. The report will be the way chosen by those who have not money, after this they must be informed of the possibility of being a party during the procedure and being assisted free of charge by a lawyer (art. 109 LECrim), because a lawsuit implies the assistance of a lawyer from the onset and with it, of having money with which to pay it (art. 277 LECrim). But after these, in both cases, the control upon the procedure passes to the State, embodied in the Examining Magistrate. According to the LECrim, the Examining Magistrate is who has the authority to admit the report or the lawsuit (art. 269 and art. 313 LECrim), event which will take place only when the facts reported in them can be classified as a crime by any of the precepts of the Spanish Criminal Code (in Spanish Código Penal, henceforth CP). Here its power is relatively constrained, because any impartial subject, even without or scarce knowledge in law, can assess if the facts reported can be regarded as a crime. Therefore, normally a lawsuit or a report should be admitted.
Once the lawsuit or report is admitted, the investigation of the crime related in it begins. In these stage of the Criminal Procedure appears another character which is also part of the State, the Judicial Police, which has the duty of investigating the crimes (art. 282 LECrim), although the LECrim still attributes the control of all the investigation upon the Examining Magistrate (art. 308 LECrim). A citizen without economic resources will have initiated the Criminal Procedure by means of a report and should have to rely altogether in the labour of these two figures, the Examining Magistrate and the Judicial Police. On the contrary, a rich citizen probably will have initiated the procedure by means of a lawsuit, which likewise will probably be supported with the work not only of lawyers, but with the contribution of even private detectives, therefore a corrupt or incompetent State cannot sway the outcome of the procedure as much as in the former case.
The investigation has to end within the period marked by the law (art. 324.4 LECrim), or when enough proofs has been gathered in order to justify an accusation during an oral trial. Achieved this stage of the Criminal Procedure a poor citizen will be assisted by lawyer who is paid by the State, and will have the proofs which the State has gathered of the crime, a rich citizen will have lawyers paid by it, and the proofs not only gathered by the State, but also by private detectives. This is really important, because here the Examining Magistrate in the Abbreviated Procedure (art. 779 LECrim) and the Tribunal trying the case in the Ordinary Procedure (art. 630 LECrim) have a power which will mark the outcome of the process, both have to decide whether the oral trial should start, or whether the cause should be dismissed. In a corrupt State, where a poor citizen has reported a crime which may embarras the its institutions here the Criminal Procedure will end with almost all certainty, on the contrary, a rich citizen with the help of its money may still have an opportunity thanks to the proofs gathered with the assistance of private investigation. 
Imagine that the Criminal Procedure continues. During the investigation the Examining Magistrate acts too as accusation, it determines the crimes which will be the object of accusation during the oral trial and their authors (art. 775 and art. 384 LECrim), without forgetting that it also leads the investigation previous to the oral trial (art. 308 LECrim), but when the oral trial starts the Judges trying the case assume an impartial paper, the prosecution is exercised by the Public Prosecutor and by the citizen offended by the crime who has decided being part of the Criminal Procedure (art. 109 LECrim). The public and private prosecution have to accuse through their writings of provisional qualification of the crime (art. 650 LECrim), nevertheless these writings must be within the boundaries marked previously by the Examining Magistrate during the investigation (art. 384 and art. 779.4), thus the private and public prosecution can accuse, yes, but according to what previously has indicated the State. 
On the Oral Trial, the impartial paper of the Tribunal may be tainted by some faculties, like asking to the witnesses questions (art. 708 LECrim), or proposing new proofs (art. 729 LECrim), so the Tribunal or Judge which exercised them must be careful of not forsaking their impartial paper, on the contrary they will have assume assume a paper of accusation which is forbidden to them. But let’s move on. At the end of the oral trial, the public and private prosecution may change their accusation, although maintaining the facts and accused (art. 732 LECrim). Now the Judge or Tribunal has to decide on the guilt or innocence of the accused. For this, they have not almost restraint, the proofs practiced during the oral trial have to be assessed by them according to the principle of free assessment of the proofs (art. 741 LECrim), which means that all is valid unless it is a flagrant error or infringement of rights. The poor citizen, with all probability will have lost the lawsuit against the State before the beginning of the oral trial, as I have said before, but the rich citizen, even having wasted resources of all sort, probably will lose too, later, at the end of the procedure, but a losing anyway, because if the sentence is duly motivated and doesn’t contain a manifest error, the assessment of the proof made by the Tribunal or Judge will be correct.
What does all this means? This is up to you, I have shown you only the way to arrive to your conclusion.