The CSR reporting requirements are regulated under the articles L. 225-100 of the French Commercial Code.
In 2001, France was the first country in EU, which introduced sustainability reporting. This law was applicable only to limited public companies. Moreover, no sanction was set out in the law.
Nowadays, the system is less lenient. Through a regulation ('ordonnance'), the directive EC 2003/51 was implemented the 22nd December 2004.
The article L. 225-100 §3 set out that a report shall be presented to the shareholders during the annual general meeting by the management board. It shall include “where appropriate, the key performance indicators of a non-financial nature which relate to the company's specific business, such as information pertaining to environmental issues and personnel matters.” The report is then published at the register of a tribunal.
In addition to this implementation of the directive, a relatively recent reform ( law 2010-788, 12th July 2010) added the following. The report shall include information about how the company takes into consideration the social and environmental consequences of its activity and about its social undertakings in favour of the sustainable development. This information must be in compliance with international treaties and European law. To implement those principles, regulations were laid down. For instance, the articles R 225-104, R 225-105 and A225-1 of the commercial code provided detailed lists on the content of the information, which shall be included in the report for the public companies. For the companies classified because of a hazardous activity, there are some specific details to provide.

Pursuant to the article L. 225-102-1, all the limited public companies, admitted to trading on a regulated market, the public companies, which have a total balance sheet or turnover and the number of workers exceeding a certain number. A decree has to fix this number (Commercial Code article L.225-102-1). The decree is still not laid down. It was supposed to be set out at the end of February. Since there is no Environment Minister any more and until the new election of the President of the Republic, I am quite pessimistic about a soon enactment of a decree.
The groups of companies are also concerned. The parent company has to gather the information of its subsidiaries (Com. C. Art L. 233-1).
Some companies under specific regulations are concerned by the CSR reporting recommendations. Are included: some insurance companies ( Code of insurance art. L . 322-26-2-2), financial companies (Code monetary and financial art. L.511-35), public companies. The UCITS annual report has to inform the investors about social and environmental issues of the investment. (Monetary and Financial Code art. L.214-23-1)

About the respect of those previsous requirements, there is a double control. First, the auditor of the company ('le commissaire aux comptes') controls the concordance between the social and environmental information provided by the report and the annual accounts (Com. C. L823-10). Second, an independent organism will also check the information with what the company actually did (Com. C. L225-102-1).

The article L225-102-1 provides no sanction in case of non-respect of the CSR reporting requirements. Nevertheless, the Directory Board has the obligation to present to the General Meeting a report including such reporting. In case of an incomplete reports, the decisions taken during the general meeting can be declared void (Com. C. art L225-121).
Moreover, the independent entity, which controlled the compliance, is entitled to investigate about the information missing in the report.

Further more, where a French company adopts voluntarily CSR principles, it may be liable in the following circumstances.
First, the workers themselves, as a part of the company, could engage their liability. The employer may write the CSR principles into the internal rules of the company called 'réglement intérieur'. In such a case, the employees can ask the enforcement of these rights (Article L1321-5 of the Labour Code). Nevertheless, the internal rules must be in compliance with the individual human rights of the employees. Usually, the Courts prefer to dismiss the application.
A company, as an employer, could also be obliged to respect CSR principles.
Indeed, the employer may practice CSR principles as a habit. In labour case law, a habit (usage) could be assimilated to a custom. In such a case, the habit is enforceable. In order to be enforceable, the worker has to prove that it was repeated regularly and considered as compulsory by the ones who submit themselves to it or who are the beneficiaries. Moreover, it must concern either all the employees or a general category of them.
Other stakeholders can also engage the company liability on the grounds of the violation of CSR principles.
The companies may also be liable for the acceptance of CSR principles to their customers.
The grounds could be a contract or its terms and conditions. It could also be the advertisements if they are furnished to the client and could be considerate as contractual obligations.
The customers could also sue the companies on the grounds of untruthful advertisements. Indeed, the article L. 121-1 of the Code of Consummation states 'All advertising comprising, in any form whatsoever, representations, information or presentations which are false or likely to mislead, is prohibited, where the latter cover one or more of the items listed hereinafter: existence, nature, composition, substantial qualities, content in useful principles, species, origin, quantity, [...] reasons for sale or service provision, sale or service provision procedures, scope of obligations undertaken by the advertiser, the identity, qualities or aptitude of the manufacturer, retailers, promoters or service providers.' Indeed, the company, which claims to respect environmental and social principles, misleads the consumer. The advertisement must concern one element of the list mentioned in the article. The list is really large, so this last condition is easy to fulfil.
Last but not least, the company that accepted voluntarily to respect CSR principles may be sued by a competitor. The Court could condemn a company, which does not respect for instance a code of conduct published. The act is considered as an act of unfair competition (concurrence déloyale), condemned under the very general article of tort liability: the article 1382 of the Civil Code. Indeed, it would be unfair that a company attracts customers from a competitor on the base of untruthful advertisements for instance.