In many criminal proceedings, such as assaults, sexual offences, gender-based violence, or harassment, the only direct witness to the events is the victim themselves: there are no recordings, no other witnesses, and no conclusive forensic evidence. Can a conviction be based solely on their statement? The Supreme Court’s answer is yes, but under demanding conditions.

The starting point of Spanish case law is that the victim’s statement constitutes valid incriminating evidence and may be sufficient on its own to convict, without the need for other elements to corroborate it. If corroboration were always mandatory, offences committed in private, precisely the most serious ones, would in practice go unpunished. But this does not mean that any statement is automatically credible: the court must subject the testimony to rigorous analysis, and if reasonable doubts arise, the outcome must be acquittal by application of the principle of in dubio pro reo.

The Supreme Court has developed a system of assessment criteria, which are not a mathematical formula but guidelines for analysis. The first is the absence of subjective lack of credibility: checking whether there is any objective reason, such as animosity, prior litigation, or financial interests, that would raise suspicion that the accusation is false or distorted. The second is objective plausibility: the internal coherence of the account and its compatibility with the circumstances of the case, since an account that changes substantially in essential respects loses reliability. The third is persistence in the incrimination: the testimony must be maintained consistently, without variation in the core elements of who, what, when, where, and how, although peripheral details may vary.

To this is added peripheral corroboration: although not essential, the existence of other elements supporting the account, such as a forensic report, prior messages, or collateral witnesses, significantly reinforces its credibility, and its absence demands greater rigour in the remaining criteria.

The defence has the right to question the victim and to challenge their version, within the right to adversarial examination, although it must exercise this with sensitivity and respect, especially where there is trauma; humiliating cross-examinations are ethically questionable and are usually counterproductive. The strategy must be based on objective evidence, not on personal disparagement. It is important to distinguish essential contradictions, which affect the identity of the perpetrator or the nature and timing of the events, from peripheral ones, which are compatible with the fragility of memory.

In offences of particular sensitivity, the assessment is more delicate: in sexual assaults, solid peripheral corroboration is usually required when the account contains inconsistencies; in gender-based violence, the victim’s retraction does not automatically extinguish liability and prior statements may be assessed; and where the victim is a minor, their statement is taken through a video-recorded forensic interview to avoid secondary victimisation. Retraction poses a complex situation: the court must assess the initial accusation and the subsequent denial with equal rigour, and if the retraction is due to pressure or fear, the original version may prevail.

In short, the victim’s testimony can sustain a conviction, but only when it withstands demanding critical analysis; if a reasonable doubt remains, that doubt benefits the defendant.