Can a secretly recorded phone call serve as evidence in a lawsuit?

In the digital age, a telephone conversation is quickly recorded. But may you use that recording as evidence in civil proceedings, for example, to prove a contractual breach by the other party? It is a question that concerns many of our clients. In an interesting ruling dated April 15, 2025, the Brussels Court of Appeal addressed this delicate issue. The ruling provides clear guidance on the admissibility of such (potentially) illegally obtained evidence.

The facts: an architect, a contractor and a hidden recording

The case involved a dispute between building owners and their architect. The building owners blamed the architect for shortcomings in carrying out renovation work on their home. To prove them right, the building owners wanted to present a crucial piece of evidence: an audio recording of a telephone conversation between the architect and the contractor. Piquant detail: the recording had been made by the contractor, unbeknownst to the architect.

The architect vehemently opposed the use of this recording and its accompanying transcription. He argued that the recording violated his right to privacy and was illegal. To strengthen his opposition, the architect even filed a criminal complaint against the building owners for illegally recording, possessing and distributing a private communication, a crime punishable by Article 314bis of the Criminal Code. He then asked the civil court to suspend the proceedings pending the outcome of the criminal case, following the well-known adage "le criminel tient le civil en état."

Appeals court's reasoning

The appeals court had to consider two main questions:

1. Were civil proceedings to be stayed pending a ruling in the criminal case?
2. Should the telephone call recording, which may have been illegally obtained, be admitted as evidence in the dispute?

1. No suspension of proceedings ("le criminel ne tient pas le civil").

The court refused to stay the proceedings. The rule that criminal proceedings take precedence over civil proceedings is there to avoid conflicting rulings. However, the court noted that the final decision in the criminal case would have no impact on the admissibility of evidence in the civil case.

For this, the court relied on the so-called "Antigone jurisprudence" in civil cases. The mere finding that evidence was illegally obtained (for example, because it is the result of a crime) does not automatically lead to its exclusion. A judge must evaluate it in light of the right to due process. Therefore, even a criminal conviction of the building owners would not necessarily mean that the evidence should be excluded in the civil case. Thus, there was no risk of inconsistency, allowing the civil proceedings to proceed as usual.

2. The recording may be used as evidence

The court then delved deeper into the heart of the matter: the admissibility of the recording itself.

• The right to privacy (art. 8 ECHR)

The architect invoked his right to privacy, as guaranteed by Article 8 of the European Convention on Human Rights (ECHR). However, the court held that this right had not been violated here. The conversation in question took place in a purely professional context. There was no indication that private elements came up during the conversation. The architect could not reasonably expect aspects of his private life to come up in a professional conversation with the contractor.

The court added that even if the right to privacy applied, there was no violation in this particular case. This was a single recording, made by a third party (the contractor) and used only for evidentiary purposes in a lawsuit, which is a legitimate purpose and not indicative of an intent to harm.

• The general rule: unlawful evidence is not necessarily inadmissible

The court reiterated the Supreme Court's settled case law: illegally obtained evidence in a civil case should be excluded only if:

1. the reliability of the evidence was affected by the illegality;
2. OR the use of the evidence compromises the right to due process.

In assessing the right to a fair trial, the judge must weigh interests and consider all the circumstances of the case.

In this case, the court saw no reason to exclude the evidence. The reliability of the recording was not affected by how it was obtained. The architect could still dispute the content and reliability of the conversation during the debates. Listening to the recording could even play in his favor if his version of the facts were correct.

Moreover, the building owners' need for proof weighed heavily. They may have had no other way to prove the alleged existence of a system of price driving between the architect and the contractor.

The court therefore decided to admit the recording and its transcription to debate.

What does this mean for you in practice?

This judgment is an important reminder of the pragmatic attitude of the Belgian courts toward evidence in civil litigation. Secretly recording a conversation is not without risks - a criminal complaint, as was the case here, is never excluded. Nevertheless, a (possible) illegality does not mean that you cannot use the evidence.

The judge will always make a concrete assessment. Crucial questions here are:

• Context: Is it a private or a professional conversation?
• Reliability: Is the recording authentic and not manipulated?
• Necessity: Do you have other means to prove your point?
• Proportionality: Isn't the invasion of the other party's privacy disproportionate to the importance of the evidence?

Are you facing a contractual dispute and have an audio recording that can support your case? Or are you yourself facing a counterparty who wants to use a secretly made recording against you? Then specialized legal advice is indispensable.

Our firm has extensive expertise in construction and contract law and in the finer points of evidence law. We can assess for you the chances of success in using such evidence and develop a strategy to maximize the preservation of your rights.