In our recent article, at Ayuela Jiménez we analysed Constitutional Court Judgment (STC) 15/2026, of 23 February, and noted that it could mark a turning point in pre-trial detention practice. The legality of what had hitherto been tolerated —that a generic “summary” or purely formal access to the incriminating evidence sufficed to order pre-trial detention— had been proscribed by the Constitutional Court.
The defence emerged strengthened, but the question was whether the ordinary courts would adopt this new standard, or whether it would remain a promising but ultimately ineffectual judgment in practice.
Well, the uncertainty was short-lived. STC 15/2026 has burst squarely into judicial practice. And it has done so in dramatic fashion: RTVE, Antena 3, Libertad Digital and numerous other media outlets have reported on the release of 24 suspects under investigation for drug trafficking within the framework of “Operación Sombra Negra” (Operation Black Shadow), one of the most significant large-scale cases recently handled by the Audiencia Nacional.
The impact has been such that the Anti-Drug Prosecution Service itself has publicly expressed “concern and uncertainty” regarding the potentially expansive reach of this doctrine and the risk of a cascade of appeals and applications for release.
The matter has ceased to be purely technical, and is generating real, visible and extraordinarily uncomfortable effects for the practice of criminal investigation in secret and complex proceedings.
Indeed, behind those headlines there is not merely media noise or institutional alarm: there are concrete judicial decisions that demonstrate the extent to which the doctrine of STC 15/2026 has begun to produce real effects.
This is clearly illustrated in Order 166/2026, of 4 March, issued by the Third Section of the Criminal Division of the Audiencia Nacional, handed down precisely within the framework of “Operación Sombra Negra”.
The defence challenged the pre-trial detention order arguing, amongst other grounds, that the essential elements of the proceedings which subsequently served as the basis for the precautionary measure had not been adequately disclosed.
The question is as simple as it is decisive: whether pre-trial detention ordered on the basis of essential elements which the defence had been unable to access or effectively challenge prior to the hearing under Article 505 of the Criminal Procedure Act (LECrim) could be considered constitutionally valid.
From this point, what is significant is not so much the reiteration of the constitutional doctrine, but rather how it is applied to the specific case. And it is here that one can see that the standard set by STC 15/2026 is not rhetorical, but operational.
The first thing the Court does is to recall that the right of access to the essential elements of the proceedings does not operate of its own motion, but rather at the request of a party. That is to say, this is a right that must be expressly invoked by the defence.
On that basis, the Court recalls the key principle: the right of access to the essential elements cannot be satisfied by means of generic or abstract information. It is not sufficient to describe the structure of the criminal organisation, nor to attribute a particular role within it to the suspect. That may serve to provide context, but not to justify a measure as severe as pre-trial detention.
What is decisive is that the defence has knowledge of the actual substance of the evidence relied upon to justify the deprivation of liberty. And it is precisely here that the decision acquires practical significance:
Despite certain documentation having been provided and an explanation having been offered at the hearing under Article 505 LECrim, the Court considers that the information given was insufficient. Reference was made to police surveillance and telephone intercepts, but without specifying results, without identifying interlocutors, without dates, without transcripts…
In other words, precisely what the Constitutional Court has just proscribed: a merely formal access that does not allow the evidence to be scrutinised or challenged.
The Audiencia Nacional sets this out clearly: it is not a matter of opening the entire case file or lifting the secrecy of the investigation, but rather of making an individualised effort to isolate and disclose those elements which are indispensable for challenging the appropriateness of the detention.
That effort was not made in this case. Neither with regard to the surveillance, the results of which are not even described, nor with regard to the telephone intercepts, for which no minimally identifiable content is provided. Everything remains concealed behind a generic invocation of investigative secrecy, without any concrete balancing exercise.
The result is inevitable: if the detention is based on such evidence, and that evidence is not made effectively available to the defence, the precautionary measure is constitutionally compromised.
Accordingly, the Court declares the nullity of the orders which imposed and confirmed the pre-trial detention and orders the release of the suspect, albeit subject to alternative precautionary measures —periodic appearances apud acta before the court, a prohibition on leaving the national territory with surrender of passport, and an obligation to give prior notice of any change of address, telephone number or email address—.
But what is truly important is not merely the immediate effect of that decision, but what it implies for the practice of criminal defence:
- The defence must focus the discussion on the specific incriminating elements underpinning the detention. The constitutional doctrine makes clear that it is not sufficient to know the type of investigative measures carried out —intercepts, surveillance or technological measures— but rather that what matters is being able to access their substance when the deprivation of liberty depends upon it.
- The lack of access or its insufficient nature must be placed on record. STC 15/2026 highlights that the effectiveness of the challenge depends on the defence having recorded what information it was unable to access and why this prevents a meaningful defence.
- Thirdly, the challenge must be framed in constitutional terms. It is not a matter of disputing the existence or sufficiency of the evidence, but rather of questioning the very validity of the measure when it has been adopted without allowing the defence access to the essential elements upon which it is based.
Thus, at the appeal stage, the key lies in articulating a clear sequence: identifying the decisive evidence, explaining why it cannot be scrutinised without access to its substance, and demonstrating the absence of individualised reasoning in the refusal.
In other words, what changes is not merely the way appeals are brought, but the way pre-trial detention is debated. The discussion no longer revolves around whether evidence exists, but around whether that evidence has been accessible to the defence in terms that allow it to be challenged.
What this Order consolidates is a change of standard in judicial practice: access to the essential elements ceases to be a formality and becomes a substantive requirement directly linked to the right of defence and to personal liberty.
It does not require the entire case file to be opened, but it does require that the defence be able to effectively scrutinise the substance of the evidence justifying the detention. When that access is merely apparent —when the substance of the evidence is replaced by generic references or conclusory summaries— the precautionary measure loses its legitimacy.
And that is what this decision confirms: that STC 15/2026 has ceased to be a constitutional warning, and has become a criterion of legitimacy for pre-trial detention.
