Wiretaps Require Well-Founded Suspicion Based on Objective Data, Not Conjecture

The interception of communications is one of the most intense interferences the State may exercise against a person under investigation. It authorises the State to listen to private conversations, access their content and use them as evidence in criminal proceedings. For that reason the legal order surrounds this measure with a set of very precise constitutional and statutory requirements, the breach of which renders the measure void and requires the exclusion of any evidence derived from it. The Supreme Court restates that threshold in a judgment handed down in proceedings for continued breaking-and-entering of an inhabited dwelling, reiterating that judicial authorisation of a wiretap cannot rest on intuition or police hypotheses but requires genuine indications: well-founded suspicions supported by objective data.

The constitutional framework: Article 18.3 CE and the LECrim

Article 18.3 of the Spanish Constitution guarantees the secrecy of communications. It may only be restricted by judicial order, which the Supreme Court has consistently interpreted as requiring authorisation that is prior, reasoned, proportionate and time-limited. At the statutory level, Articles 588 bis a) et seq. and 588 ter a) et seq. of the LECrim, introduced by Organic Law 13/2015, set out the formal and substantive requirements of the measure: the authorisation order must state the facts grounding the measure, the indications that the person under investigation has committed or is committing an offence, the scope and duration of the measure, and the police unit carrying it out.

These requirements are not mere formalities. They are the guarantee that the judge does not act as a rubber stamp for police requests but exercises genuine and independent scrutiny before authorising the interference. Where that scrutiny is omitted or limited to reproducing the content of the police application without independent assessment, the order is constitutionally defective in a way that cannot be remedied.

The indications standard: what the Supreme Court requires

The Supreme Court's case law has defined with precision what constitutes sufficient indications to authorise a wiretap. A mere subjective suspicion on the part of the investigating officer is not enough. What is required is objective, externalisable and verifiable data that enables the judge to check, independently, that there is a reasonable basis to believe that the suspect is committing or is about to commit an offence, and that the measure is necessary and proportionate to obtain the evidence.

Among the elements the Chamber considers insufficient to ground authorisation, settled doctrine identifies the following: a bare reference to the fact that the subject "is known in criminal circles", generic assertions about criminal activity without specifying observed facts, or a simple reference to a criminal record with no direct connection to the offence under investigation. The police application must describe specific observations, documented surveillance, human intelligence of sufficient reliability or any other external data that the judge can weigh independently.

Consequences of the breach: exclusion of derived evidence

Where the interception of communications is authorised without the required factual grounding, the wiretap becomes unlawful through breach of Article 18.3 CE. In procedural terms, the direct consequence is exclusion: the recorded conversations cannot be admitted as evidence for the prosecution, and evidence derived from them is equally tainted unless it can be shown that it would have been obtained through an independent line of investigation.

This exclusionary rule — known in the common law tradition as the fruit of the poisonous tree doctrine and anchored in Spanish law in Article 11.1 of the Organic Law on the Judiciary — operates objectively: it does not depend on the good or bad faith of the officer who requested the measure, but on the constitutional breach that the wiretap represented. A defence that succeeds in establishing that breach at trial may achieve the partial or total exclusion from evidence of all material obtained through the interception.

Practical challenge of the wiretap in criminal proceedings

From a defence perspective, the analysis of the validity of a communication interception begins with a close examination of the authorisation order and the police application that preceded it. The inquiry should focus on whether the order expresses the indications in the judge's own terms — not merely reproduced from the police document — and on whether the factual description in the application is sufficiently specific to ground a judicial authorisation.

Nullity may be raised at different stages of the proceedings: in the provisional conclusions, by way of preliminary plea where available, or at the oral trial in the preliminary issues phase. In all cases it is important to build the challenge around the documents on the case file — the police report, the authorisation order and any extensions — rather than on generic arguments, since the court will assess the sufficiency of the indications on a case-by-case basis, examining what the investigating judge actually had before him at the time the order was made.

A repeatedly affirmed doctrine of the Supreme Court

The judgment under discussion does not open a new doctrinal line: the requirement of objective indications for authorising telephone interceptions is well-established Supreme Court case law, applied across a wide range of contexts — drug trafficking, economic offences, organised crime — and not only in property offences. Its significance lies precisely in that reiteration: the Supreme Court insists on the standard even in cases where the gravity of the offence under investigation might tempt a more relaxed approach to scrutiny. The message is clear: the seriousness of the offence does not lower the constitutional requirement for a reasoned authorisation order.

For criminal defence practice, this doctrine has immediate practical value. In any case where wiretaps are the backbone of the prosecution, examining the factual sufficiency of the authorisation order is the first step in analysing the evidence. An interception built on police hypotheses unsupported by objective data not only compromises the evidence it produced: it may compromise the entire investigative structure raised upon it.