What is an abusive sick leave ?
An abusive sick leave is sick leave that is medically unjustified. The employee is therefore granted sick leave without a valid medical reason. The fraudulent nature of the sick leave is established when the employee fails to comply with the obligations associated with their sick leave. To verify this, the employer may challenge the sick leave through a medical examination, an objective analysis of the facts and, if deemed necessary, may engage a licensed private investigator to make the necessary findings.
Not only does an abusive sick leave represent a loss for the company, but it also constitutes fraud against the National Health Service, as the employee receives daily sickness benefits. Legally, the employee must strictly comply with certain conditions for their sick leave to be valid. This raises a key question: how can one prove that sick leave is being taken fraudulently? This is precisely the role of a private investigator specialising in employment law.
Who is entitled to commission an investigation into a dispute relating to an abusive sick leave claim ?
Any employer who has suffered a loss due to an employee’s absenteeism may engage a private investigator. Whether it is an SME, a large corporation or a tradesperson, engaging a private investigation agency is legal and governed by law. The investigator will be able to build a solid case to prove the fraudulent sick leave.
What are the options for a private investigator to intervene in a case involving fraudulent sick leave ?
The private investigator can employ various investigative methods, such as tailing, targeted surveillance, or administrative checks regarding the employee, in order to establish whether the sick leave is fraudulent.
The private investigator may thus:
- Follow and discreetly monitor the employee, for example to assess their state of health.
- Verify compliance with authorised departure times.
- Detect physical activity incompatible with the sick leave (sport, work, travel, etc.)
- Identify any undeclared or competing professional activity.
- Arrange a second medical examination at an appropriate time.
- Drawing up an objective, detailed and admissible report
The risks faced by the employer in the event of an error, when acting in breach of the law, expose them to a labour tribunal ruling, the nullification of the disciplinary procedure and damage to the company’s reputation. This is why professional support is essential.
What evidence can a private investigator provide in case of fraudulent sick leave ?
Once the private investigator has provided evidence of an abusive sick leave claim, the employer may then cease payment of supplementary benefits, impose disciplinary sanctions or even, in certain exceptional cases, proceed with dismissal. The evidence provided by the private investigator in relation to an abusive sick leave claim may also be used in the event of an appeal to the Employment Tribunal, provided that the employee under surveillance has been given prior notice that a private investigator may monitor them (Article L1222-2 of the Labour Code).
The private investigator produces an investigation report on the monitoring of employees, often accompanied by photographs or videos taken in public spaces, at times when the employee is supposed to be available for any medical checks or to comply with rest instructions. This visual evidence is time-stamped and geolocated without any editing or subjective commentary. In such cases, the private investigator notes the dates and times of each observation, where they took place, the nature of the activities observed, as well as their duration and frequency.
Cost : how much does it cost to hire a private investigator in a labour law case ?
Hiring a private investigator in cases of suspected fraudulent sick leave often costs less than the actual loss suffered by the company.
Our fees start from €60 per hour (excluding VAT) and average around €80 per hour (excluding VAT) for a licensed agent, depending on the nature and requirements of the assignment.
For this type of assignment, we generally prefer daily flat rates, which include all costs from the outset, to ensure complete transparency and better budget control. Please contact us by phone or email to arrange a free, personalised, no-obligation quote.
Which sections of the law deal with abusive sick leave ?
The legal framework for abusive sick leave is based on a fundamental requirement of good faith. According to Article L1222-1 of the Labour Code, the employment contract must be performed in good faith, a principle that the employer may invoke if an employee misuses their sick leave. This requirement for sincerity applies from the moment the sick leave is prescribed: Article R4127-28 of the Public Health Code prohibits doctors from issuing a certificate or report of convenience, thereby ensuring that the absence is based on a genuine and serious medical justification.
Under Article L1226-1 of the Labour Code, employers who pay additional salary to supplement Social Security benefits have the right to verify the legitimacy of the sick leave. This provision has been significantly strengthened by Decree No. 2024-692 of 5 July 2024, which imposes an increased obligation of transparency and availability on the employee. For the medical review to be valid, the employee must now specify their place of rest and, even where ‘free to leave’ is stated, indicate time slots during which they will be present at their home. If the appointed doctor concludes that there is no medical justification or if they are prevented from carrying out the examination (incorrect address, unexpected absence, refusal of access), the employer is legally entitled to suspend payment of the employer’s share of the salary for the remainder of the sick leave.
At the same time, the employee is subject to strict obligations towards the health insurance scheme. Article L323-6 of the Social Security Code establishes the principle of refraining from any unauthorised activity. An employee is therefore deemed to be acting abusively if they carry out professional work, engage in a leisure activity incompatible with their condition, or fail to comply with medical instructions. Under Article L323-7, failure to comply with these rules, as established during an inspection, may result in the suspension of daily benefits. In this context, Articles L315-1 to L315-3 confer upon the Social Security medical adviser the role of arbitrator regarding the legitimacy of the sick leave. The medical adviser ensures continuous monitoring and, in the event of a breach — such as failing to attend an appointment without a valid reason — benefits are suspended. Finally, if a disagreement arises between the attending doctor and the medical adviser regarding whether the sick leave is abusive, Article L315-3 provides for the appointment of a medical expert to settle the dispute.
What are the main legal precedents regarding abusive sick leave?
Case law from the Court of Cassation has gradually tightened the penalties for engaging in paid work whilst on sick leave, placing the duty of loyalty at the heart of the debate. In a recent judgment of 25 June 2025 (No. 24-16.172), the High Court thus clarified that engaging in paid work, even for a very short period, may be sufficient to constitute serious misconduct. In this approach, the financial loss suffered by the company is not the decisive factor: it is the moral breach of the duty of loyalty that is penalised. This severity is all the more pronounced when the activity is competitive. The judgment of 28 January 2015 (No. 13-18.354) further establishes that working for oneself or for another employer in the same sector of activity whilst on sick leave constitutes serious misconduct, the harm to the employer being presumed by the act of competition itself.
However, classifying the misconduct requires a detailed analysis of the circumstances. Whilst undeclared work for a competitor or an activity materially incompatible with the declared medical condition justifies immediate termination of the contract, the Court of Cassation reiterates in its judgment of 26 February 2020 (No. 18-10.017) that it is imperative to demonstrate either actual harm to the employer or a clear breach of contractual obligations. In addition to these prohibited activities, the employee must also comply with their attendance obligations. Thus, the judgment of 26 September 2012 (No. 11-18.937) confirms that an employee’s absence during an employer-arranged medical re-examination, outside authorised leave periods, entitles the employer to immediately suspend continued payment of wages, thereby penalising a breach of monitoring rules.
To establish such breaches, the employer may now rely on forms of evidence that were previously more contested. Whilst the case law of 28 January 2015 (No. 13-27.980) already permitted the use of a private detective’s report to prove concurrent employment, the landmark ruling of the Plenary Assembly of 22 December 2023 (No. 20-20.648) has radically transformed the rules governing the admissibility of evidence. By establishing a principle of proportionality, the Court now allows the judge to accept evidence obtained by unfair or unlawful means, provided that it is essential to the exercise of the right to evidence, proportionate to the stakes involved and justified by legitimate interests. In practical terms, the use of a private investigator is now permitted if it involves discreet, temporary and targeted surveillance in public places, thereby providing the employer with an impartial third-party tool to document misconduct whilst respecting the employee’s privacy.
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