Joris DeeneAnyone who searches through another person’s private messages is, in principle, acting unlawfully. However, that does not automatically mean that evidence obtained in this manner will be excluded from criminal proceedings. In a Judgment of May 26, 2026 The Court of Cassation ruled that a judge may apply a less stringent standard when assessing irregularities committed by a private individual than when assessing those committed by the police or the public prosecutor’s office. The ruling clarifies both what constitutes a valid complaint in a complaint form and how the Antigoon test applies when it is not the government but a citizen who has unlawfully obtained evidence.
The facts
The case involves a defendant who was convicted on appeal, in part for possessing images of child sexual abuse. Part of the evidence came from emails that the victim’s mother had viewed on a computer left behind in the former family home, and from data retrieved from a cell phone.
In his statement of appeal, the defendant had checked only one box under the heading “Procedure”: he reserved the right to raise procedural arguments regarding the authenticity of the findings at the appellate level. It was not until his brief on appeal that he requested the exclusion of the emails and cell phone data as unlawfully obtained evidence.
The Antwerp Court of Appeal ruled that his guilt regarding the possession of the visual material had been definitively established, since the statement of appeal did not contain a valid ground of appeal on that point. The defendant filed an appeal to the Court of Cassation against that judgment, citing two grounds.
The decision
The Court of Cassation dismisses the appeal in its entirety. The decision is based on two distinct legal issues.
A reservation is not a grievance
Pursuant to Article 204, paragraph 1 Code of Criminal Procedure The appellant must file a statement of grounds for appeal within the appeal period that precisely sets forth the grounds on which he challenges the judgment, failing which the appeal will be dismissed. The Court reiterates its established definition: a ground of appeal is the specific identification of a separate decision within the judgment under appeal that the appellant seeks to have reversed.
According to the Court, a mere reservation made by checking a box—an indication that one intends to argue a particular point—lacks the clarity and precision required to qualify as a ground for appeal. The appellate court is not required to take such a reservation into account. The procedural objection to the emails and cell phone data was therefore not raised in a timely and proper manner, so that the conviction for possession of the visual material had become final. The alleged violation of Art. 6 of the ECHR and Art. 14 of the ICCPR was derived from that same, unsuccessfully raised claim of illegality and was therefore declared inadmissible.
A private individual may be subject to less stringent scrutiny than the government
The second ground of appeal challenged the Court of Appeals’ ruling regarding the Antigone test. The court had accepted that the evidence remained admissible, in part because the unlawfulness was not committed by an investigative or prosecuting authority, but by the victim’s mother, who acted on her own initiative and had no special prior knowledge of the course of the criminal proceedings.
The Court of Cassation upholds that ruling. When assessing whether the collection of evidence results from an intentional or equivalent irregularity that constitutes gross negligence, the judge must take into account all relevant information, including the knowledge, experience, and information that the person concerned is deemed to possess. In doing so, the court may apply a less stringent standard to a private individual than to a professional investigative or prosecutorial official. The distinction made by the appellate court between the conduct of a citizen and that of such an official is therefore by no means impermissible. The part of the appeal that challenged the appellate court’s findings of fact required an examination of facts over which the Court of Appeal has no jurisdiction and was therefore declared inadmissible.
Legal analysis and interpretation
The ground for appeal remains a strict filter, even for procedural objections
The first principle is consistent with a long-standing line of reasoning since the introduction of the grievance system by the Potpourri II Act. The description used by the Court—the specific identification of a separate decision for which a review is sought—is the same as that used by the Constitutional Court in its judgment No. 2/2018 stipulated. Since the amendment to the law explicitly incorporated procedural objections into Article 204, that strict standard also applies to procedural challenges: anyone seeking to argue for the exclusion of evidence must raise it as a separate objection, not as a general reservation.
The application of this rule to a checked reservation is, in that sense, no surprise, but it does provide a useful clarification. The ruling makes it clear that filling in the “Procedure” section with a statement of future arguments does not extend the appellate court’s jurisdiction. The line between excessive formalism and meaningless flexibility, which the Court of Cassation has guarded in previous case law, is drawn firmly on the strict side here: a reservation is not a decision submitted for review and therefore falls outside the devolutive effect of the appeal.
The criterion set forth in the April 4, 2023, ruling does not apply in full to citizens
The second part is the most interesting. In a judgment dated April 4, 2023 The Court ruled that irregularities committed intentionally, or those resulting from gross negligence, “are, in principle, incompatible with the loyalty and regularity of the collection of evidence that must be expected in a state governed by the rule of law from the prosecuting and investigating authorities.” In such cases, the evidence must generally be excluded on the basis of the right to a fair trial, as assessed against Article 32 Preliminary Title of the Code of Criminal Procedure.
The May 26, 2026, ruling lays bare the limits of that case law. It is now explicitly clear that the strict rule from 2023 was formulated with the government in mind. The Court confirms that, when applying the same test—intent or gross negligence—the trial court may take the perpetrator’s status into account, and thus may subject a private individual to a less stringent standard. The rationale is logical: the allegation of unfair evidence gathering presupposes an actor from whom professional diligence and knowledge of the rules of procedure may be expected. A parent who looks at messages on a shared computer does not fit that profile.
At the same time, this line of reasoning warrants critical scrutiny. The Antigoon framework primarily protects the individual concerned from unreliable evidence and an unfair trial; from the defendant’s perspective, it does not necessarily matter for the impact on their defense rights whether the violation was committed by a public official or by a private citizen. The judgment shifts the focus from the protected interest of the defendant to the culpability of the evidence gatherer. This is defensible within the existing criteria, but it illustrates how broad the trial court’s margin of discretion under Art. 32 VTSv. has become.
The factual assessment is not subject to review by the Court of Cassation
The third part of the second ground of appeal challenged the factual finding that the mother acted on her own initiative and without prior knowledge. The fact that the Court dismisses this as a matter of fact confirms that the weighing of the Antigoon criteria is largely left to the unchallengeable assessment of the trial court. The Court of Appeal merely reviews whether that court does not draw unreasonable conclusions from its findings—a marginal review that, in practice, makes the outcome highly dependent on the factual context.
Specifically, what does this mean?
For those who file an appeal in criminal cases. The appeal form leaves no room for ambiguity. Anyone wishing to raise a procedural objection—such as a motion to exclude evidence, a challenge to the probative value of evidence, or a preliminary objection—must identify it as a separate, precisely defined ground of appeal within the appeal period. A checked box under the “Procedure” heading is insufficient and excludes the relevant decision from the appellate court’s jurisdiction. It is advisable to formulate each ground of appeal positively as a specific decision of the trial court that one seeks to have overturned, and not as an announcement of future arguments.
For anyone who wants to report a crime based on evidence they have gathered themselves. Evidence obtained by a private citizen in an unlawful manner is not automatically inadmissible. The court applies a more lenient standard when assessing the conduct of a private individual than it does for the police or the public prosecutor’s office, especially when the person in question acted on their own initiative and in good faith. Nevertheless, the violation may have consequences in another area: the unauthorized viewing or disclosure of another person’s private communications may in itself constitute a civil or criminal offense. The admissibility of the evidence in the criminal case says nothing about the liability of the person who gathered it.
For those who are confronted with evidence gathered by a private individual. A defense seeking to exclude such evidence cannot rely solely on demonstrating unlawfulness in and of itself. The test is conducted under Article 32 of the Code of Criminal Procedure, under which the capacity of the person gathering the evidence is a mitigating factor. A challenge is more likely to succeed when it focuses on the reliability of the evidence or on a concrete violation of the right to a fair trial, and when it is raised in a timely manner and as a valid ground for appeal.
Frequently asked questions (FAQ)
Is evidence that my ex-partner obtained from my emails admissible in criminal court?
Not automatically invalid. A judge applies the Antigoon test and may assess the conduct of a private individual less strictly than that of the government. Whether the evidence is accepted depends on the specific circumstances: did the person involved act in good faith, on their own initiative, and does the evidence remain reliable and the process fair?
What constitutes a valid grievance on a grievance form?
A ground for appeal is a specific reference to a particular part of the judgment that you are seeking to have overturned. A vague reservation or a mere statement that you will present arguments at a later date does not constitute a ground for appeal and excludes the relevant part of the judgment from the Court of Appeals’ review.
Can I still raise procedural arguments in my brief that were not included in my statement of claims?
Only for decisions that have been brought before the appellate court through a valid appeal. Procedural objections to a decision that was not raised as part of the appeal are too late: that decision has then become final.
Conclusion
The judgment of May 26, 2026, confirms two matters that often coincide in practice. From a procedural standpoint, the complaint form remains a strict filter: a reservation is not a complaint, and anyone who fails to clearly identify procedural criticism as a separate complaint permanently forfeits that criticism. In terms of substance, the Court refines the Antigoon test by confirming that the strict standard for intentional or grossly negligent irregularities, formulated for the government in the judgment of April 4, 2023, does not apply in full to private individuals. In this regard, the trial court retains a broad margin of discretion that largely escapes review on appeal.
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