When we find in the criminal jurisdiction a procedure against one or more individuals that is based on witnesses who have not seen anything for themselves and that what they contribute is what the direct witness has told them, what probative value has this so-called reference witness?
The jurisprudence of the Chamber of the Supreme Court has had the opportunity to rule on this type of testimony on numerous occasions and as stated in STS 597/2017, of July 24 (RJ 2017, 3989) ,
«[…] this Cassation Chamber has established that the reference witnesses cannot provide a greater proof of the event that occurred than that which would be obtained from the referenced testimony itself, because what they only know are the statements heard from it. The certainty that certain affirmations were made by the direct witness is the only thing that can result from the veracity of what they declared, and, consequently, there remains the need to weigh and assess the direct testimony to determine the fact that is intended to be ascertained. The reference testimonies, still admitted in art. 710 of the LECrim, thus have a limited demonstrative effectiveness regarding the criminal act, since going directly from what was truthfully declared by the hearsay to having as proven without further ado what was affirmed by the one who was heard would be equivalent to privileging an extra-procedural narrative stolen from immediacy and contradiction. For this reason, the value of the reference testimony is that of complementary evidence to reinforce what is accredited by other evidence, or that of a subsidiary evidence, to be considered only when it is impossible to go to the direct witness, because their identity is unknown, they have died. or for any other circumstance that makes his witness statement impossible. And even in this case, the demonstrative weakness of the reference witness is evident to support by itself a pronouncement of conviction, due to the very nature of the source of its knowledge, which is indirect or mediate with respect to the criminal act, and always conditioned as its credibility depends on that which the direct witness deserves, despite the impossibility of being questioned and heard in the presence of the Court ( SSTS 31/2009, of 27-1 ; 129/2009, of 10-2 (RJ 2009, 446) ;681/2010, of 15-7 ; 757/2015, of 30-11 ; 586/2016, of 4-7 ; y 415/2017, of 8-6 (RJ 2017, 2909) )[…]».
Therefore, we will always have to be on the specific case, but if we have a direct witness and also a reference witness, this second testimony, by itself, would not be enough to disprove the presumption of innocence, but as a complement or reinforcement of direct testimony it can have evidentiary relevance, as a corroborating element, if applicable.