The new Private Investigation Act, in force since 16 December 2024, imposes strict rules on employers for their internal investigations.
Without adaptation, evidence of dismissals could be invalidated. A challenge that should not be underestimated.
Private investigation activities: employers are also targeted!
The new act defines the obligations, roles and responsibilities of those involved in private investigation activities (any activity consisting of gathering information about natural or legal persons or acts committed by them).
Employers are therefore affected when they call in private investigators, but also when they carry out internal investigations, either via a dedicated internal service or on an occasional basis (e.g. via the human resources department). In the first case (dedicated internal service), prior authorisation must be obtained from the FPS Interior. In the second case, such authorisation is not required, but certain rules must nevertheless be complied with.
Internal regulations updated for December 2026
The act stipulates that employers may only carry out investigations on their employees if an internal regulation sets out the procedures for doing so. Employers have until 16 December 2026 to comply with this obligation. If they fail to do so, all evidence collected will be automatically invalidated. Having such regulations in place will therefore become crucial when it comes to dismissals for serious cause.
Investigation procedure: new constraints to protect the individuals concerned
The act also lays down detailed regulations and procedures (which also apply to occasional investigations carried out by human resources departments).
For example, interviews may only be conducted after the interviewee has been informed of certain rights (right to be assisted, right to terminate the interview at any time, etc.). Interviews must also be documented in reports sent to the interviewees. Certain interview techniques are also prohibited.
Similarly, all acts of investigation must be recorded in a register. Under certain conditions, a full investigation report must be drawn up and sent to the principal (the employer in our case). If the employer decides not to use the report, it must be destroyed. If the employer decides to use the report (e.g. for dismissal for serious cause), the persons concerned must be informed and be able to exercise their right to access and rectify the data processed.
Finally, the new act also prohibits the collection of certain data. This applies in particular to political opinions, genetic or biometric data, as well as involvement in or membership of trade union organisations.
Oversight and sanctions
A number of the obligations set out in the new law are prescribed on pain of nullity. Evidence obtained in breach of these obligations will therefore be automatically disregarded, with no room for discretion on the part of the courts. This applies in particular to the obligation to have regulations in place, to obtain prior authorisation (where applicable) or to prohibit the use of certain investigation methods.
Failure to comply with other obligations (e.g. documentation of the investigation process) does not automatically render evidence null and void, and it is up to the courts to decide whether or not such evidence should be disregarded. It is still strongly recommended to comply with these provisions, particularly in the context of dismissals for serious cause.
The impact of the constraints resulting from this new law should not be underestimated: companies are responsible for putting in place a set of rules and a well-functioning operational process, even for carrying out occasional investigations. Otherwise, there is a risk that a great deal of evidence obtained in the context of dismissals for serious cause will be discarded... without the facts justifying those dismissals even being examined. You've been warned!
Julien HICK, Partner, AKD Benelux law firm & Heleen FRANCO, Senior associate, AKD Benelux law firm
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