Le client mystère, une preuve recevable dans la procédure de licenciement

Faced with the abundance of litigation concerning the monitoring of employee activity by the employer, our labour Law team has taken an interest in the contours of this power. A ruling handed down on September 6 by the Court of Cassation (1) clarifies the admissibility of evidence of an employee’s misconduct, constituted by the intervention of a mystery-shopper commissioned by the employer.

In civil matters, evidence cannot be obtained unfairly and/or illegally.

The Social Division of the Cassation’s Court has on several occasions reiterated this principle, ruling out as evidence any element gathered by means of a control and surveillance device set up without the employee’s knowledge.

For example, a recording made by a camera hidden near the employee’s workstation has been ruled unenforceable (2).

Similarly, evidence gathered by witnesses sent by the employer to surprise and verify the actions of a sales assistant while cashing goods was deemed illegal (3).

However, recently, in a ruling handed down on September 6, the Cassation’s Court (4) ruled that evidence gathered by means of a mystery shopper was lawful and therefore admissible.

Does this mean that employers are now allowed to prove an employee’s misconduct using evidence derived from an unfair stratagem ?

Hasty conclusions should be avoided.

The Court of Cassation has clarified the contours of this type of evidence. In this case, an employee of a self-service restaurant was dismissed for serious misconduct, the employer accusing him of failing to comply with the company’s cash-in procedures, specifically by not giving the customer a receipt when cashing up.

To prove this fault, the employer produced a “mystery shopper” report, who had been commissioned by the employer to carry out checks. The “mystery shopper” had noted that no receipt had been issued after the requested amount had been cashed.

The employee took his case to the Labour Court, seeking a ruling that his dismissal was without real or serious cause, on the grounds that the employer had used an unfair stratagem to make this proof unlawful.

The Court of Cassation ruled that the Aix-en-Provence Court of Appeal had legally justified its decision in rejecting the employee’s request. It ruled that, in accordance with the provisions of article L. 1222-3 of the Labor Code, the employee had been expressly informed, prior to its implementation, of this professional assessment method implemented by the employer. Consequently, the employer was entitled to use the results in support of a disciplinary procedure.

In this case, the Appeal’s Court (5) had noted that the employee’s prior information was attested to by the employer’s production of a Social and Economic Committee (ESC) meeting report mentioning the mystery-shopper visit, and a note informing employees about the mystery-shopper stratagem, explaining how it worked and its purpose.

Proof of misconduct by means of a mystery-shopper is therefore admissible under certain conditions, the first of which is that the employee must have been informed in advance of the existence of such a control.

A control technique widely used by franchised brands in the hotel, restaurant and sales sectors, the use of “mystery shoppers” is increasingly spreading to new business sectors, prompting employers to ensure that employees are informed of the existence of such a control system in the event of litigation.

A decision that echoes previous Court of cassation case law.

This ruling appears to echo previous case law on the monitoring of employee activity by means of video or sound recordings. The employer may monitor employee activity during working hours. However, he must inform the ESC and the employees of the implementation and use of the monitoring means and techniques. Failing this, the evidence obtained from the system is in principle considered illegal (6).

(1) Cass. soc., sept. 6/2023, no 22-13.783.
(2) Cass. soc., nov. 20/1991, no 88-43.120.
(3) Cass. soc, nov. 19/2014, no 13-18.749.
(4) Cass. soc., sept. 6/2023, no 22-13.783.
(5) Cour d’appel d’Aix-en-Provence 7B, 01-07-2021.
(6) Cass. soc., march 14/2000, no 98-42.090.



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Bénédicte Litzler
Aurélie Davoult
Elora Boscher

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