For over a decade, Spanish criminal procedural law has included a key safeguard to ensure that a suspect in proceedings subject to secrecy (secreto de sumario) can effectively exercise their right of defence: their lawyer may (or, as will be seen, may only theoretically) have access to the essential elements of the proceedings underlying the arrest (Articles 520.2(d) and 505.3 of the Criminal Procedure Act, as amended by Organic Law 5/2015 of 27 April).
The rationale was clear: to strengthen the right of defence and prevent situations in which an individual could be provisionally deprived of liberty without truly knowing the accusations against them or the specific evidence supporting such a decision.
However, in practice, this reform did not alter investigative dynamics. In many cases declared secret, access to the “essential elements” was limited to the delivery of the pre-trial detention order and a brief, generic indication of the type of evidence on which the decision was based, without disclosing its actual content.
The reasoning was always the same: the secrecy of proceedings, as provided for in Article 302 of the Criminal Procedure Act, is intended to protect the investigation and prevent risks such as destruction of evidence, coordination among suspects, or frustration of ongoing investigative measures. Under this logic, disclosure of certain materials was considered capable of jeopardising the success of the investigation. Examples of this approach can be found in decisions such as Orders of the National Court (AAN) 832/2025 of 19 December; 818/2025 of 17 December; and 443/2025 of 8 July.
The result was a clear inconsistency that significantly undermined the right of defence. A suspect could be remanded in custody without any real opportunity to explain their version of events with minimum guarantees, as the defence lacked access to the documentation supporting the request for detention. In other words, the prosecution had access to the full body of incriminating material, while the defence was required to challenge pre-trial detention with only minimal access to its evidentiary basis.
This was the practical reality: a guarantee recognised in law, but interpreted in a minimalistic manner in its effective scope.
For its part, the Constitutional Court has long been aware of this tension. Its case law has consistently held that secrecy is constitutionally legitimate, but must be applied restrictively, proportionately, limited in time, and without undermining the right of defence or causing material indefensibility.
This is a long-standing issue. As early as Constitutional Court Judgments 13/2017 of 30 January and 21/2018 of 5 March, the Court held that the right to personal liberty requires that the suspect be granted access to the essential elements justifying their detention. This doctrine was subsequently extended to pre-trial detention in secret proceedings in rulings such as Constitutional Court Judgments 83/2019 of 17 June; 94/2019 and 95/2019 of 15 July; and later 180/2020 of 14 December; 80/2021 of 19 April; 4/2023 of 20 February; 30/2023 of 17 April; 68/2023 of 19 June; and 152/2023 of 20 November.
In particular, Judgment 83/2019 (Legal Ground 5) and Judgment 180/2020 (Legal Ground 4) emphasised that access to essential elements is intended to enable the defence to “objectively verify the accuracy and consistency of the information received” in order to challenge it effectively. This is not a matter of procedural courtesy, but a guarantee of equality of arms.
Moreover, in Judgment 21/2018 (Legal Ground 7(c)), the Court provided an illustrative list of what may constitute essential elements: incriminating complaints, witness statements, expert reports, recordings, search records, inspections, or the collection of evidence. This reasoning was reiterated in the context of pre-trial detention in Judgment 180/2020.
However, what remained unresolved—at least in practice—was the precise scope of such access. It is precisely at this point that the Constitutional Court Judgment of 23 February 2026 (appeal for constitutional protection No. 2153/2025) takes a further step.
The core issue was straightforward: the suspect had been provided with a document entitled “Summary of the content of the allegations (…) by which the essential elements of the proceedings are communicated,” yet this document contained only a generic description of the alleged offences and indications, without specifying or individualising the actual content of the evidence underpinning the detention.
Formally, the court had complied: it delivered a document prior to the hearing under Article 505 of the Criminal Procedure Act and allowed the defence to make submissions. Substantively, however, the issue was different: did this constitute real and effective access to the essential elements, or merely apparent compliance?
The Constitutional Court acknowledges that, from a formal perspective, information had been provided in due time and form. However, it stresses that the decisive factor is not the appearance of compliance, but whether the material disclosed enabled an effective defence:
“In summary, ‘formal’ access to the proceedings consisting of a generic reference to the type of source, but devoid of content or including only a partial account of the information, does not guarantee the right of defence, as it prevents or hinders the challenge to the decision depriving the individual of liberty.”
The document referred to the offences under investigation (criminal organisation, public health offences, and bribery) and mentioned certain indications, including an intercepted telephone conversation. However, it did not identify the conversation, the devices involved, its full content or transcription, nor the context in which it occurred.
This is the decisive point: that conversation constituted the main indication of the suspect’s involvement and the essential basis for ordering pre-trial detention. Despite this, the judicial authority denied access to the recording or its transcription, merely asserting that the information provided was sufficient and that disclosure would harm the investigation.
The Constitutional Court is unequivocal: the secrecy of proceedings cannot serve as a basis for excluding access to the essential elements underpinning the deprivation of liberty. Moreover, the refusal was not accompanied by an individualised reasoning explaining why that specific conversation was not essential or why its content could not be disclosed. A generic reference to risks to the investigation was made, without any specific balancing exercise.
The conclusion is clear: by failing to provide access to the conversation constituting the core evidentiary basis for detention, the possibility of a real and effective challenge was undermined. Accordingly, the Court finds a violation of the rights to personal liberty (Article 17.1 of the Spanish Constitution) and to defence (Article 24.2), annuls the contested decisions, and grants constitutional relief.
The consequence is the nullity of the pre-trial detention. Looking ahead, where detention is prolonged, this doctrine may have a tangible economic impact ex post; where it is brief, its practical effect may be more limited.
Nevertheless, the significance of this judgment lies at a strategic level: it strengthens challenges against detention orders based on merely formal access to information, making it more difficult for a generic “summary” to suffice as justification for deprivation of liberty. The defence now benefits from stronger constitutional support to demand real and effective access to the evidentiary material underpinning precautionary measures. However, its full impact will depend on its adoption by the courts.
Ultimately, this judgment once again highlights the limits of a practice that had progressively emptied a fundamental safeguard of its substance. Access to the “essential elements” cannot be symbolic or generic when personal liberty is at stake.
