{"id":11169,"date":"2025-11-13T09:43:31","date_gmt":"2025-11-13T09:43:31","guid":{"rendered":"https:\/\/groupehyperion.com\/evidence-obtained-by-a-private-detective-in-employment-law-what-the-law-says-in-2025\/"},"modified":"2026-07-30T07:37:37","modified_gmt":"2026-07-30T07:37:37","slug":"evidence-obtained-by-a-private-detective-in-employment-law-what-the-law-says-in-2025","status":"publish","type":"post","link":"https:\/\/groupehyperion.com\/en\/evidence-obtained-by-a-private-detective-in-employment-law-what-the-law-says-in-2025\/","title":{"rendered":"Evidence obtained by a private detective in employment law: what the law says in 2025"},"content":{"rendered":"

Disputes<\/a> between employers and employees are becoming increasingly complex. Suspicious sick leave, unfair competition<\/a>, misappropriation… Faced with these situations, how can an employer prove their allegations without crossing the red line of respecting privacy? <\/p>\n

In recent years, French case law has undergone a major shift: investigation reports drafted by licensed private detectives are now increasingly being accepted before labour courts. But be careful—this admissibility is not automatic. It is governed by specific rules, which we will break down. <\/p>\n

At Groupe Hyperion, private detective in Montpellier<\/a>, we regularly support companies in Hérault, Toulouse, Perpignan and Annecy in building strong cases for their labour disputes<\/a>.<\/p>\n<\/div><\/div>

Before 2023: when fairness prevailed above all<\/strong><\/h2>\n

Just two years ago, the situation was relatively straightforward for judges: any evidence obtained “unfairly” was excluded from the proceedings. In practical terms, this meant that discreet surveillance<\/a>, a recording made without the employee’s knowledge, or even unauthorised screenshots could not be presented in court. <\/p>\n

The principle was clear: you cannot infringe a person’s fundamental rights, even to establish the truth. This employee-protective stance sometimes left employers powerless in the face of blatant abuses they were unable to document legally.<\/p>\n<\/div><\/div>

2023–2025: the case-law turning point<\/strong><\/h2>\n

Everything changed with several recent rulings from the Court of Cassation and the growing influence of the European Court of Human Rights. Judges now take a more balanced approach, based on two cumulative criteria: <\/strong><\/span><\/p>\n

Indispensability:<\/strong> the evidence must be the only realistic way to establish the facts. If other probative elements exist (witness statements, internal documents, admissions), the “unfair” evidence will be rejected. <\/p>\n

Proportionality:<\/strong> the infringement of the employee’s rights must remain strictly limited to what is necessary. Several months of surveillance<\/a> will be deemed excessive where a few days would have sufficed. <\/p>\n

This development marks a real turning point:<\/strong> the right to evidence is no longer systematically sacrificed in the name of fairness. Judges now assess each situation on a case-by-case basis.<\/p>\n<\/div><\/div>

Five recent decisions illustrating this development<\/strong><\/h2>\n

Several cases decided between 2023 and 2024 help clarify where the line is drawn:<\/strong><\/span><\/p>\n

March 2023<\/strong> – An employee produces colleagues’ payslips to demonstrate pay discrimination. The Court of Cassation upholds this evidence: it was indispensable and the infringement of the colleagues’ rights remained proportionate to the objective pursued. <\/p>\n

September 2023<\/strong> – An employer uses the “mystery shopper” technique after informing teams of this possibility in the internal regulations. The evidence is deemed fully fair and admissible. <\/p>\n

December 2023<\/strong> – Conversely, an employer who produces non-anonymised medical files is met with a categorical refusal: the infringement of privacy is disproportionate.<\/p>\n

January 2024<\/strong> – A clandestine recording intended to prove workplace bullying is excluded, because other witness statements and written exchanges existed. The evidence was therefore not indispensable. <\/p>\n

May 2024<\/strong> – Latest twist: the Court overturns a ruling that had rejected a recording without even examining the substance of the case. Message to judges: every piece of evidence deserves a contextual assessment. <\/p>\n

When should you call on a private detective in employment law?<\/strong><\/h2>\n

Companies regularly call on our services to document situations where evidence is difficult to establish otherwise. Here are the most common cases we handle in Montpellier and throughout the Occitanie region: <\/span><\/strong><\/p>\n

Fraudulent sick leave<\/a>: an employee on sick leave who carries out professional activity or leisure activities incompatible with their declared health condition. Our surveillance<\/a> makes it possible to establish the facts objectively. <\/p>\n

Unfair competition<\/a>:<\/strong> an employee bound by a non-compete clause who works for a competitor or solicits your clients. We document these actions with precision. Read our article on unfair competition<\/a> and admissible evidence<\/a>.<\/a><\/p>\n

Remote-work abuse:<\/strong> repeated absences from home during working hours, or carrying out an undeclared side activity.<\/p>\n

Internal theft or misappropriation:<\/strong> identifying and documenting fraudulent behaviour within the company. See our professional investigation services for businesses.<\/a><\/p>\n

In each of these situations, the report we produce can make all the difference at a labour court hearing.<\/p>\n

What makes a detective’s report admissible in court<\/strong><\/h2>\n

An investigation report cannot be improvised. For it to be accepted by a judge, it must meet several strict requirements: <\/strong><\/span><\/p>\n

Absolute objectivity:<\/strong> we simply describe what we observe factually, without interpretation or judgement. No “he seemed nervous” or “he gave the impression that”—only verifiable findings. <\/p>\n

Full traceability:<\/strong> every observation is time-stamped, geo-located and documented. If we mention an appointment, we specify the exact time, the precise location and the duration. <\/p>\n

Respect for privacy:<\/strong> we never enter a home, hack any IT system, or collect sensitive personal data without a legal basis. Our investigations are limited to public places and information that is legally accessible. <\/p>\n

Proportionality of the investigation:<\/strong> we adapt the duration and intensity of surveillance<\/a> to what is strictly necessary. Three days of surveillance<\/a> may be enough where a client was considering fifteen. <\/p>\n

These safeguards are not optional:<\/strong> they determine whether our reports are admissible. That is why, at Groupe Hyperion, we continuously train our investigators on legal developments. <\/p>\n

The legal framework for our profession<\/strong><\/h2>\n

Our activity is strictly governed by the Internal Security Code. Article L621-1 precisely defines our mission:<\/strong><\/span> to gather information intended for third parties to defend their interests.<\/p>\n

To practise legally, every private detective must:<\/p>\n