Search and seizure is one of the most intrusive measures in criminal proceedings, and its execution frequently exceeds the limits of what was originally authorized.
When, in the course of a lawful investigative measure, law enforcement officers discover evidence of a crime different from the one that prompted the measure, this is referred to as serendipity or the fortuitous discovery of evidence.
The problem is that this same justification may also conceal investigative measures that, from the outset, had no clearly defined objective — the so-called fishing expedition.
This article addresses the practical difficulty of distinguishing between these two phenomena, with particular attention to cases involving cell phones and digital data, and examines how the Superior Court of Justice (STJ) has addressed the issue in recent decisions.
Serendipity and the Fortuitous Discovery of Evidence
Serendipity describes a situation in which state agents, while carrying out a duly authorized investigative measure, come across evidence of a crime different from the one that motivated the measure. Legal scholarship distinguishes between objective serendipity — the discovery of a different criminal offense — and subjective serendipity, which occurs when the involvement of persons other than those initially under investigation is discovered.
Recognition of a fortuitous discovery depends on three requirements:
- the original investigative measure must have been lawful;
- the discovery must have been genuinely unforeseeable, rather than the result of an investigative measure designed, even informally, to produce it;
- the agents must have remained within the limits of what had been judicially authorized.
Fishing Expeditions and the Limits of Criminal Investigation
A fishing expedition is an exploratory investigative measure carried out without a minimum evidentiary basis, with the purpose of indiscriminately searching through a person’s life, documents, or devices in the hope that incriminating material will emerge. It reverses the logic that should guide an investigation: instead of investigating based on indications of wrongdoing, the investigation is conducted in order to generate such indications.
Article 240, §1, of the Brazilian Code of Criminal Procedure (CPP) makes a residential search conditional upon the existence of reasonable grounds, which cannot be equated with the mere abstract possibility of finding something relevant. Nor does a judicial warrant constitute unrestricted permission: it defines the location, the object of the search, and, in the case of electronic devices, the scope of the measure.
This distinction has become particularly important with cell phones. Seizing a device found during a lawful investigative measure is one act. Examining its contents — messages, photographs, geolocation data — is another, with a far broader impact on privacy. Treating these two stages as inseparable is one of the points at which the line between serendipity and a fishing expedition is most easily blurred.
Between Fortuitous Discovery and Speculative Search
No single criterion operates in isolation or functions as an automatic formula. Among the factors relevant to assessing the legality of evidence obtained during search and seizure are the original purpose of the measure, the existence of reasonable grounds, the objective limits of the warrant, the relationship between the object under investigation and the evidence discovered, and the conduct of the agents during execution of the measure.
One point deserves particular emphasis: the distinction between seizing an object found incidentally and independently investigating its contents. Presuming that the lawful possession of a cell phone, by itself, authorizes unrestricted access to its contents gives serendipity a scope that it cannot legitimately have.
There is also the problem of retroactive justification: the result obtained cannot validate the means employed. If the investigative measure was speculative from the outset, the production of relevant evidence does not transform a fishing expedition into a fortuitous discovery.
STJ Case Law: Three Cases, Three Degrees of Authorization
Three recent STJ decisions illustrate how these criteria are applied — and where the greatest tensions lie.
In HC No. 1,030,471/SP, police officers were executing an arrest warrant when the defendant himself confirmed that he was keeping drugs at home. There was no search warrant. The court rejected the fishing-expedition argument because case law does not require the resident’s specific authorization for entry when executing an arrest warrant (Article 293 of the CPP), and because the search resulted from the defendant’s own statement rather than from an indiscriminate search.
In AgRg in REsp No. 2,269,660/SP, a co-defendant’s cell phone was seized while a preventive arrest warrant was being executed — rather than a search-and-seizure warrant. The court upheld access to the data as a fortuitous discovery, citing precedent concerning cell phones seized “in execution of a search and seizure warrant.” The cited precedent, however, involved a different procedural instrument from the one used in the case at hand: the reasoning developed for warrants that already authorize the collection of electronic devices was extended to an arrest warrant, whose purpose is to apprehend an individual, not to obtain digital evidence.
In AgRg in RHC No. 228,503/ES, there was a search and seizure warrant expressly issued for the address in question, explicitly authorizing the collection of “cell phones, computers, media [and] storage devices.” The cell phone seized belonged to the defendant’s son, who was not named in the warrant. The court upheld the seizure because the relevant criterion was not the identity of the property’s owner, but rather the objective scope of the order with respect to the location and the type of material sought.
The three cases reached the same result — the evidence was deemed admissible — but they rested on different factual premises concerning the degree of judicial authorization supporting the investigative measure. This gradation rarely appears in the headnotes, but it is crucial to understanding the limits of each precedent.
The Extension of an Arrest Warrant as a Point of Concern
The first two cases reveal an issue that deserves attention. An arrest warrant has a single purpose: to authorize the apprehension of a person. It was not conceived as an instrument for conducting searches, much less as a legal basis for examining digital content.
When the STJ extends to this instrument reasoning developed for search and seizure warrants, there is a risk of undermining the distinction between the two legal mechanisms.
This does not mean that every seizure carried out during the execution of an arrest warrant is unlawful. However, the absence of judicial authorization specifically directed toward the collection of evidence should require more rigorous reasoning than that applied in cases where the search itself had already been authorized in advance.
Final Considerations
Serendipity is recognized under Brazilian criminal procedure, but that recognition cannot become a blanket authorization to investigate any fact or person on the grounds that everything resulting from a lawful investigative measure is automatically legitimized.
The discovery of a crime does not eliminate the question of how and why the investigative measure was conducted in that particular manner. That question remains the most reliable criterion for distinguishing legitimate serendipity from a fishing expedition disguised as chance.
