How to conduct an internal investigation into harassment or discrimination: interviews, impartiality, GDPR and probative value of the report?

Updated 9 November 2026

Key contacts: Pascal-André Gérinier (Lawyer - Founder), William Mak (Lawyer - Founder)

An internal investigation carries weight before the court if it is fair, impartial, proportionate and documented: written scoping, investigators with no connection to the facts, interviews of the complainants, the witnesses and the implicated person, written records read over and signed, data processed in accordance with the GDPR, a report that distinguishes established facts from unestablished facts. The Cour de cassation leaves it to the court to assess the probative value of the report in the light of the other evidence (Cass. soc. 18 juin 2025, n° 23-19.022): it is the method that makes the evidence, and a report produced incompletely weakens the employer's position.

Key points

Apart from the GDPR, none of these rules is a legal obligation: they are good practices, whose absence weighs on the value of the report.

• Two investigators per interview, one who leads, the other who takes notes; written record read over and signed on the spot.
• The complainant, the witnesses, then the implicated person, to whom the facts are put so that they can respond.
• A written scope for IT searches: accounts, period, keywords; never a personal mailbox.
• The GDPR applies: information of individuals, data minimisation, retention period, the employee's right of access to their professional emails.
• A report organised fact by fact, on three levels: established, unestablished, uncorroborated; produce everything, or explain why not.

The strength of an investigation depends on its method as much as on its conclusions. The court examines the fairness of the interviews, the impartiality of the investigators, the opportunity given to the implicated person to respond and the quality of the documents preserved. It assesses the report in the light of the other evidence, as Cass. soc. 18 juin 2025, n° 23-19.022 points out. No provision of the French Labour Code requires, in itself, an internal investigation to establish facts of harassment (Cass. soc. 14 janvier 2026, n° 24-19.544, handed down in a sexual harassment case); it is, on the other hand, required after an alert from an elected works council (CSE) member. It remains the most reliable means of documenting a decision. A rushed investigation weakens the employer and the employees concerned alike.

1. Scope the investigation in writing

Everything begins with a written document: an engagement letter if a lawyer is appointed, a scoping note otherwise. It sets out the facts concerned, the scope (persons, departments, period), the investigators, the timetable in weeks, the recipient of the report and the confidentiality rules. It specifies how individuals will be informed of the processing of their data, as the GDPR requires, and how the works council is involved: compulsorily where an elected member has triggered the alert under Article L. 2312-59 of the French Labour Code or the alert for serious and imminent danger (Article L. 4132-2), by choice otherwise. Finally, it recalls the time limit: two months to initiate disciplinary proceedings from the time the facts are precisely known (Article L. 1332-4), which rules out investigations that drag on. For a report received through the whistleblowing channel, a prior step applies: check that it falls within the scope of the system, then acknowledge receipt within seven working days (Decree No. 2022-1284 of 3 October 2022, Article 4).

2. Take protective measures

Protect the person reporting the facts quickly. Consider, with their agreement, a temporary adjustment of the organisation, without imposing a transfer or removal on them against their will. A report made in good faith must not lead to any retaliatory measure (Articles L. 1152-2 and L. 1152-3 of the French Labour Code). As regards the implicated person, prefer, if necessary, a paid exemption from work, notified as a non-disciplinary protective measure. A precautionary suspension requires in principle that the disciplinary procedure be initiated without delay, unless there is a valid reason, in particular waiting for the conclusions of the investigation (Cass. soc. 30 octobre 2013, n° 12-22.962). Also preserve the evidence: frozen copies, access logs, access rights, without opening any personal mailbox.

3. Choose the investigator and rule out conflicts of interest

The investigator must have no hierarchical or personal link with the complainant or the implicated person, and must not themselves be a witness to the facts. Where management or the HR director is concerned, the investigation is entrusted to an external party mandated by the competent body, the board or the chairman. Two investigators are better than one: one leads the interview, the other takes notes and reads them over. Depending on the facts, the lawyer involves professionals whose role is set out in writing: a chartered accountant or an auditor for financial flows, a digital forensics specialist for mailboxes and servers, the data protection officer, an occupational psychologist for collective situations of distress, local counsel for a site abroad. The guide Why entrust the internal investigation to a lawyer? compares the practitioners; the Internal investigations page presents the firm's method.

4. Conduct the interviews

The summons states the general purpose of the interview and recalls the confidentiality expected. At the start, explain who is conducting the investigation, for which principal and within what framework. Where the investigator is a lawyer, make clear to the person interviewed that they are not the lawyer's client and, if facts could be alleged against them, that they may be assisted by a lawyer, in accordance with the profession's ethical rules. As a rule, interview the complainant first, then the witnesses, and finally the implicated person. Put the alleged facts to the latter with enough precision to obtain their answers. Two investigators make note-taking easier and limit disputes. Ask open, chronological and factual questions, without pressure or suggesting answers. Have the written record read over and signed on the spot, or record the refusal to sign. Arrange for an interpreter or a bilingual lawyer if necessary.

An interview framework comes down to six stages: what the person observed themselves, and what they learnt from others; when, where and in whose presence; what happened just before and just after; the writings, messages or documents that exist; the people they spoke to about it at the time; what they wish to add or correct after reading over. Closed questions and the investigator's hypotheses have no place in it.

Some situations are common. The witness who retracts or refuses to sign: no legislation obliges them to; the refusal and its reason, the retraction and its date are recorded, without comment, and corroboration is sought in the documents. The anonymous report: verification on the documents first, a written decision whether or not to open an investigation, interviews afterwards, without naming the person concerned as long as nothing implicates them. Conflicting accounts with no physical evidence: the report says so, fact by fact, and a complainant whose account is not confirmed is not thereby in bad faith, which can result only from knowledge that the reported facts are false (Cass. soc. 7 février 2012, n° 10-18.035). Old facts: check whether they are continuing or have only just come to light. The implicated executive: a mandate from the competent body and secured access before the first interview. In all cases, no pressure on the persons interviewed, and protection of witnesses acting in good faith against any retaliatory measure (Article L. 1152-2). A witness statement in the form required by Article 202 of the French Code of Civil Procedure may be requested later from those who agree.

5. Digital investigations: how far to go

Emails and files created with the company's tools are presumed to be professional: the employer may consult them without the employee being present, unless they are identified as personal. The rule comes from the Cour de cassation: the Nikon judgment of 2001 established the secrecy of personal correspondence at work (Cass. soc. 2 octobre 2001, n° 99-42.942), then the presumption that emails not identified as personal are professional was laid down (Cass. soc. 15 décembre 2010, n° 08-42.486). The investigation itself is not a system for monitoring activity subject to prior information (Cass. soc. 17 mars 2021, n° 18-25.597), but surveillance tools, video, geolocation or targeted logging, are (Article L. 1222-4). Personal telephones and private messaging services may not be consulted by the employer; material derived from them is admitted in court only if its production is indispensable to the right to evidence and strictly proportionate (Ass. plén. 22 décembre 2023, n° 20-20.648). In practice: a written scope (accounts, period, keywords), a frozen copy made by the IT department with a digital fingerprint, exclusion of items marked personal, a log of operations, and a court bailiff (commissaire de justice) to record what will have to be produced. Never open a personal mailbox, even with the help of a colleague who knows the password.

The processing of data must rest on a legal basis, legal obligation or legitimate interest as the case may be, and not on the consent of employees, which the imbalance of the employment relationship makes in principle unsuitable (Article 6 and recital 43 of the GDPR). Inform the persons concerned (Articles 13 and 14). Limit the data collected and their retention to what is necessary (Article 5). Deal with access requests within one month, extendable by two months (Article 12). The employee may access the emails in their professional mailbox, metadata and content included, unless this infringes the rights of others (Cass. soc. 18 juin 2025, n° 23-19.022; Article 15 of the GDPR). Preserve the rights of witnesses. If the whistleblowing system applies, comply with the enhanced confidentiality provided for in Article 9 of the Sapin II Act. Involve the data protection officer from the scoping stage.

6. Keep to the time limits

Three time limits run at the same time. Two months to initiate disciplinary proceedings from the day on which the employer has precise knowledge of the reality, nature and extent of the facts (Article L. 1332-4): an investigation necessary to acquire that knowledge postpones that starting point, provided it is not dilatory; it runs earlier if the employer already knew. Seven working days to acknowledge receipt of a whistleblower report and three months to inform its author of the outcome. Finally, the investigation "without delay" required by an alert from an elected works council member. The guide Which HR risks require an internal investigation to be opened? details the interplay of these time limits.

7. Write the report

The report first describes the mandate, the scope and the method, then reconstructs the timeline. Each fact is examined separately, on three levels: established, unestablished or uncorroborated. It indicates the documents and statements relied on, the contradictions and the exculpatory elements. It avoids premature legal characterisations and distinguishes findings from recommendations. The written records are annexed, and an anonymised version is prepared with a view to possible production in court. In the case decided on 18 June 2025, the production of five of fourteen interview records, without justification or explanation of their anonymisation, weakened the evidence: preserve the entire file and justify any omission. Shortcomings are not sufficient, in themselves, to exclude the report, except where unlawful investigations have been carried out (Cass. soc. 29 juin 2022, n° 21-11.437).

8. Decide on the follow-up

Once the report has been delivered, the employer decides quickly. If misconduct is established, the summons to the preliminary meeting is sent within two months; the sanction is proportionate to the facts found and, before the court, the benefit of the doubt goes to the employee (Article L. 1235-1 for dismissal, Article L. 1333-1 for other sanctions). If the facts are not established, a reasoned closure is notified to the complainant and to the implicated person alike, and organisational measures may be taken without a sanction: separation of teams, training, mediation, reminder of the rules. Informing the complainant of the outcome, without disclosing third parties' interview records to them, is good practice; the author of a report made through the whistleblowing channel, for their part, receives written feedback within three months. A follow-up review at three and six months checks that the situation has been resolved. MOSAIK supports this follow-up, up to the labour court (conseil de prud'hommes) if one of the parties brings a challenge.

Quality control, phase by phase

An investigation is defended before the court through the record of its method. Each phase has a corresponding control, documented in the file.

What changes according to the facts

Alert from an elected works council member: investigate without delay together with them (Article L. 2312-59 of the French Labour Code). Whistleblower: protect identities (Article 9 of the Sapin II Act), acknowledge receipt within seven working days and give feedback on the outcome within three months (Article 4 of the Decree of 3 October 2022). Discrimination: keep the objective justifications for your decisions, because, once the employee presents facts suggesting discrimination, it is for the employer to prove that they are unrelated to any discrimination (Article L. 1134-1). Sexual harassment: prevent the conduct, put an end to it and sanction those responsible (Article L. 1153-5). Internationally, check the language of the interviews and local law. To dismiss a protected employee, apply for authorisation from the labour inspectorate, which will examine the investigation.