Private investigator and employment law: evidence and fraudulent sick leave
- RIVIERA PRIVATE INVESTIGATION
- 5 days ago
- 4 min read
I. Introduction
The involvement of private investigators in employment law cases raises complex questions at the intersection of labor law, the law of evidence, and respect for individual liberties. In a context where fraudulent sick leave is perceived as a significant source of costs for businesses and social security, some employers are considering using private investigations to establish the facts. However, the French legal framework is particularly protective of employees' privacy, requiring a rigorous analysis of the admissibility of the evidence collected.
II. Applicable legal framework
A. The right to privacy and evidence in social law
In French law, the concept of respect for private life is a fundamental principle enshrined in both Article 9 of the Civil Code and the case law of the Court of Cassation. This principle prohibits the use of evidence obtained unfairly or in a way that infringes upon an employee's privacy. Traditionally, the courts considered any evidence obtained without a person's knowledge, consent, or legal basis to be unlawful and irregular.
B. Recent case law on the admissibility of evidence
However, an important jurisprudential turning point has occurred since 2020-2023. By plenary assembly judgments of December 22, 2023, the Court of Cassation admitted that, under strict conditions of proportionality and indispensability, evidence obtained in a potentially unlawful manner can be taken into account in a civil and social dispute, provided that it is indispensable to the exercise of the rights of the litigant and that it does not disproportionately infringe upon fundamental rights (including privacy).
This reversal means that judges, including in employment matters, must now assess the legality and proportionality of the means of proof on a case-by-case basis, rather than automatically dismissing any "unfair" evidence.
C. Professional supervision of private detectives
Private investigators operate a regulated profession governed by the Internal Security Code. They must be licensed by the CNAPS (National Council for Private Security Activities) and adhere to a strict code of ethics, particularly regarding respect for privacy and professional secrecy.
III. The role of private investigators in combating fraudulent sick leave
A. Nature of missions and legal limits
The intervention of a private investigator may consist of:
verify compliance with obligations related to work stoppage (authorized outing times);
to observe activities incompatible with the declared state of health;
to establish innocent behaviors that may shed light on the judge's assessment.
However, these missions must be conducted under strict conditions of legality: surveillance limited to public places, without any stratagem likely to violate privacy, and with proportionality of the means implemented in relation to the legitimate goal pursued.
B. Legal Value of Detective Reports
French case law confirms that detective reports can be presented as evidence in court, provided they are obtained without disproportionate intrusion into privacy. Once a report meets these conditions—observations in public places, absence of fraudulent activity—it can be admitted by labor courts or courts of appeal to support disciplinary action or dismissal for misconduct.
IV. Significant Case Law (Recent Examples)
A. Cassation, January 28, 2015 (No. 13-18.354)
The French Court of Cassation has ruled that a private investigator's report is admissible as evidence in a case concerning an unjustified sick leave. In this case, an employee on sick leave was working for a competing company, necessarily causing harm to her employer: a breach of the duty of loyalty. The dismissal for serious misconduct was upheld, with the investigator's report serving as conclusive evidence.
B. Recent rulings (2021-2022)
Several decisions (e.g. Cass. soc., March 17, 2021, No. 18-25.597; Cass. soc., January 5, 2022, No. 20-21.665) remind us that detective reports can justify dismissal if the employee is engaged in an activity incompatible with a work stoppage, provided that the investigations respect privacy.
C. Case law on admissibility in employment law matters
Labour courts have ruled that the production of private detective reports is lawful when they result from observations in public places without intrusion into private life, particularly when considering the proportionality of the means employed.
V. Conditions of admissibility and legal risks
A. Proportionality and respect for freedoms
The courts balance the legitimate interests of the employer with the protection of privacy. A disproportionate investigation – intrusive surveillance, extensive tracking – may be deemed unlawful and lead to the inadmissibility of evidence or to the employer being found liable for violating fundamental rights.
B. Integration of other means of proof
To strengthen the case, employers often combine private investigator reports with bailiff's reports (now "judicial officers"), which benefit from a strong presumption of veracity, or with other elements (statements, testimonies, internal documents).
C. Risk of nullity or conviction
Case law includes examples where the use of a private investigator has been sanctioned when it has been deemed disproportionate or unlawful – for example, surveillance used in violation of prior notification obligations, resulting in a conviction for invasion of privacy.
VI. Conclusion
The involvement of private investigators in employment law matters, particularly in combating fraudulent sick leave, is governed by a demanding legal framework. While investigators can indeed play a significant evidentiary role, their use must be regulated by respect for the right to privacy, the proportionality of investigative methods, and the requirements for professional accreditation.
Recent French case law – notably the 2023 reversal on the admissibility of evidence obtained potentially unlawfully under certain conditions – opens up new perspectives, while confirming the need for strict jurisprudential arbitration between the interests of employers and the protection of employees.
