Private Investigation Act (PIA): mandatory internal regulations required by 16 December 2026

Since 16 December 2024, internal investigations concerning employees must comply with the Private Investigation Act (PIA). Employers conducting such investigations are required to adopt internal regulations governing these activities. A transitional period of two years, calculated from the entry into force of the Private Investigation Act, has been provided for the implementation of these regulations. This transitional period expires on 16 December 2026. In the absence of such internal regulations, the investigation risks being declared null and void.

1. To whom does this obligation apply? 

The scope of application of the Private Investigation Act is very broad: any employer wishing to conduct an investigation concerning employees falls within its scope. The size of the company, the number of employees, or the frequency of the investigations are irrelevant in this respect. As soon as an employer carries out private investigation activities with regard to employees (e.g., investigations into fraud, unfair competition, etc.), it must have internal regulations that comply with the Private Investigation Act.

2. What is the deadline for implementing the internal regulations?

The Private Investigation Act entered into force on 16 December 2024. The legislator has provided for a transitional period of two years during which employers must adopt internal regulations setting out the detailed rules governing private investigations in the workplace. Accordingly, such regulations must be implemented no later than 16 December 2026.

Companies are advised to begin this process promptly in order to meet this deadline. During the current two-year transitional period, it remains permissible to conduct a private investigation without internal regulations (provided that the other provisions of the Act are complied with), but this will no longer be possible after 16 December 2026.

3. What must be included in the internal regulations? 

The internal regulations must explicitly and transparently set out the authorisation to conduct private investigations, as well as the detailed rules governing such investigations.

Although the Private Investigation Act itself provides limited guidance on the specific content of these regulations, the explanatory memorandum indicates that the regulations must ensure the highest possible level of transparency towards employees and establish clear arrangements within an enforceable framework. The regulations should therefore, inter alia, address the following:

• the situations in which private investigations may be initiated; 
• the persons or departments authorised to carry out such investigations; 
• the manner in which private investigations are conducted; 
• the possible investigative measures, such as conducting interviews, searching workplaces, lockers, or company documents, analysing camera footage and geolocation data, etc.; 
• the possible consequences of a private investigation; 
• the rights of the employees concerned during and after the investigation.

4. Form: collective labour agreement, work rules or policy?

The Private Investigation Act does not specifically prescribe the form in which the internal regulations must be adopted. According to the explanatory memorandum, the regulations may, among other options, be laid down in a collective labour agreement or in the company’s work rules.

It is considered defensible that an employer implements the regulations through an internal policy unilaterally drafted, adopted, and amended by the employer.

The Act does not require formal approval from the relevant consultation bodies. However, information and consultation through the usual social dialogue channels (e.g., the works council, trade union delegation, or employees) is strongly recommended.

5. Risks of non-compliance 

Compliance with the obligation to have internal regulations in place is essential. The Private Investigation Act indeed provides that this obligation is prescribed on pain of nullity.

Evidence collected after 16 December 2026 in the context of a private investigation, where no internal regulations are in place, therefore risks being considered unlawful and consequently may not be taken into account by the court in legal proceedings. This may seriously undermine the employer’s position, for example in disputes relating to dismissal (whether or not for serious cause).

It is therefore essential that employers not only have compliant internal regulations in place, but also can demonstrate that employees have been effectively and sufficiently informed. This may be done, inter alia, through acknowledgment of receipt of the policy or through publication on the intranet combined with targeted communication to staff.

Key message

Every employer is, sooner or later, required to conduct an investigation involving employees. It is therefore essential to ensure, before 16 December 2026, that internal regulations compliant with the Private Investigation Act are in place and have been properly communicated. We remain at your disposal to assist you with the drafting and implementation of these regulations.