Navigating the Labyrinth of Belgium’s Private Investigations Act: Procedural Rules for Internal Workplace Investigations

By Legal Affairs Reporting Desk
Published: Special Compliance Series (Part 2)

Main Facts: The High Stakes of Internal Workplace Investigations in Belgium

For decades, corporate internal investigations have been treated as standard, private administrative tasks. When an employer suspects internal fraud, harassment, data breaches, or policy violations, HR departments or internal audit teams routinely launch fact-finding missions. However, following the stringent implementation guidelines of Belgium’s Private Investigations Act (PIA), the legal landscape surrounding these inquiries has drastically shifted.

As established in the first installment of this ongoing legal analysis, the PIA’s jurisdiction is deceptively broad. It does not merely apply to external, trench-coat-wearing private detectives operating in the shadows; it applies directly to internal corporate investigations carried out within a company structure.

While HR professionals conducting "incident investigations" concerning their own corporate employees may enjoy a partial exemption—specifically from holding a formal private investigator’s identification card and licensing requirements—they are by no means above the law. Every other substantive and procedural mandate outlined in the PIA applies in full force to internal corporate actors.

Failure to comply with these meticulous rules carries severe consequences. Evidence gathered improperly can be declared legally inadmissible in court, severe administrative fines can be levied by regulatory bodies, and companies can face intense scrutiny from the Data Protection Authority (DPA). As organizations scramble to adapt, understanding the strict procedural mechanics of the PIA—from pre-investigation documentation to final report destruction—has never been more vital for Belgian employers and multinationals operating within the country.

Chronology: The Lifecycle of a Compliant Belgian Workplace Investigation

Navigating a workplace investigation under the PIA requires strict adherence to a chronological framework. Missing a single procedural step can invalidate the entire proceeding, rendering months of investigative work legally useless.

[Pre-Investigation] ──> [Active Investigation] ──> [Post-Investigation] ──> [Archiving / Destruction]
• Legitimate Interest     • Strict Methodologies     • 30-Day Notification     • 3-Year Retention
• Written Assignment      • Consensual Interviews    • Final Report Submission • Mandatory Deletion
• Internal Regs Check     • Anti-Entrapment Rules    • Evidence Assessment     • Secure Storage

Phase 1: Before the Investigation Begins

Before a single question is asked or an email server is queried, employers must clear two major legal hurdles:

1. Establish a Legitimate Interest: The employer must formally possess a legitimate, verifiable interest in the investigation’s outcome. This must be meticulously documented in a written investigation assignment document prior to the investigation’s commencement (or logged in the official assignment register if handled by an internal investigation service).
2. Verify Internal Regulations: An investigation into an employee is strictly prohibited unless the possibility of conducting such an internal investigation is expressly, clearly, and transparently enshrined in the company’s internal regulations.

Phase 2: Active Investigation and Interviews

Once the investigation is greenlit, investigators must operate within tightly defined legal boundaries:

• No Special Powers: Investigators possess no special legal enforcement rights or public powers. They are restricted to standard civil rights and specific permissions granted explicitly by the PIA. They cannot infringe upon the fundamental rights and freedoms of the subjects.
• Property Access: Investigators are legally barred from entering non-public spaces (such as private offices or restricted areas) without the explicit written consent of the person who has actual enjoyment of that space, or their legal appointee.
• The Interview Process: Interviews can only proceed if the subject explicitly consents. Investigators are legally forbidden from using leading questions, suggestions, psychological threats, or coercive tactics that could compromise the interviewee’s freedom of response. Detailed context must be provided prior to questioning. Furthermore, any audio or visual recording requires prior, explicit consent (ideally captured on the recording itself), and the interviewee is legally entitled to a complimentary copy of the recording. Every interview must yield a formal written report.
• The Anti-Entrapment Principle: Investigators are strictly prohibited from acting as agents provocateurs. They cannot induce a subject to commit an offense, policy breach, or error that they would not have otherwise committed on their own initiative.

Phase 3: Post-Investigation and Reporting

• Drafting the Report: No later than one month following the final investigative act, the assignment holder must issue a comprehensive, written investigation report. This document must bear the physical or digital signature of the assignment holder and all participating private investigators. In acute emergencies, an initial oral briefing is permitted, provided it is followed by a written report within eight working days.
• The 30-Day Notification Rule: Once the final report is formally submitted, the principal (the employer) has exactly thirty days to state in writing to the investigator whether they intend to act upon the information. Employers generally face two distinct scenarios:
  1. Scenario A: Immediate action is taken (e.g., disciplinary dismissal, filing criminal charges, restructuring).
  2. Scenario B: No immediate action is taken, but the report is archived as a foundational baseline for a potential future investigation should new facts emerge. (Employers opting to hold the file for future contingencies are strongly advised to formally select this second scenario).

Phase 4: Archiving and File Destruction

The legislative lifecycle of a workplace investigation file is strictly finite:

• The Three-Year Rule: The complete investigation file must be securely retained for precisely three years from the date it was transmitted to the principal.
• Mandatory Destruction: Once the three-year statutory period elapses, the file must be permanently destroyed.
• Data Minimization: Throughout its lifecycle, the data collected must remain adequate, relevant, and strictly limited to what is necessary for the stated purpose. Disclosure to third parties is unlawful unless strictly required for the defense of the employer’s legitimate interests as outlined in the initial assignment document. Public disclosure is strictly prohibited.

Supporting Data & Legal Safeguards: What is Prohibited?

Under the PIA, the scope of permissible inquiry is heavily restricted. The law explicitly bars investigators from gathering, processing, or disclosing certain categories of sensitive information to the employer.

Prohibited Fields of Investigation

While specific statutory prohibitions cover sensitive personal data points (such as trade union membership, religious beliefs, political affiliations, or private sexual behavior), the law goes a step further: indirect inference is entirely forbidden.

An investigator cannot circumvent the rules by gathering peripheral data from which the employer can easily deduce protected categories of information without engaging in further intelligence gathering.

Evidentiary Standards and Court Scrutiny

When employment disputes, wrongful termination claims, or criminal referrals reach a court of law, the judiciary is mandated to verify whether the findings of a private investigation were obtained in strict accordance with the PIA.

Courts can—and do—strip investigative findings of any legal effect under specific conditions:

1. If the investigation was conducted without a prior written assignment or legitimate interest.
2. If fundamental rights, freedoms, or anti-entrapment rules were violated during the process.
3. If unlawfully obtained data or evidence gathered through criminal or prohibited means was utilized.

Nuance in Adjudication: It is important to note that a single procedural misstep does not automatically invalidate an entire investigation. If an employer utilized multiple working methods to establish the same set of facts, an unlawful method does not automatically taint findings that are independently supported by correctly applied, lawful investigative techniques.

Official Responses and Regulatory Enforcement

The enforcement mechanism underpinning Belgium’s Private Investigations Act is multifaceted, carrying significant regulatory exposure for non-compliant businesses.

Supervision and enforcement are shared across multiple powerful entities:

• The Data Protection Authority (DPA): Given that workplace investigations inherently involve the processing of personal data under the EU General Data Protection Regulation (GDPR), the DPA plays a central enforcement role. Every official report establishing an infringement of the PIA is automatically forwarded to the DPA.
• Police Services & Designated Inspectors: Specialized inspectors appointed by Royal Decree, alongside national police services, hold active auditing and oversight powers.

The Twofold Sanctioning Arsenal

Employers face a dual-threat compliance landscape. A violating organization can face penalties from designated sanctioning officers—who possess the authority to issue formal warnings, propose binding settlements, or levy heavy administrative fines. Simultaneously, because violations of investigative protocols frequently intersect with data protection failures, the DPA can deploy its complete sanctioning arsenal, resulting in substantial financial exposure and reputational damage.

Implications for Corporate HR and Legal Teams

The operational reality for businesses operating in Belgium requires an immediate, proactive overhaul of internal compliance policies. Organizations can no longer treat internal investigations as ad-hoc, informal conversations between HR and troubled employees.

Key strategic takeaways for corporate leadership include:

• Pre-Planning is Mandatory: Companies must draft standardized templates for investigation assignments, ensuring that a "legitimate interest" is legally articulated before any inquiry begins.
• Internal Regulations Deadline: Employers must review and update their company internal regulations to explicitly account for the legal possibility of internal investigations. With regulatory milestones fast approaching—including the critical internal regulations compliance deadline of December 16, 2026—legal teams must act swiftly.
• Training and Protocol: HR professionals who benefit from the exemption regarding licensing identification cards must still be rigorously trained on investigative interviewing techniques, anti-entrapment protocols, and strict data retention limits (the three-year destruction rule).

As workplace disputes increasingly find their way into Belgian labor courts, the admissibility of corporate evidence will hinge entirely on meticulous adherence to the Private Investigations Act. For businesses, adopting a rigorous, legally compliant investigative framework is no longer just a best practice—it is an absolute legal necessity.

Part 3 of this special legal series will focus on the most pressing calendar obligation for Belgian employers: drafting and implementing compliant internal regulations ahead of the upcoming statutory deadline.