T was employed by the CNAVTS as a “rédacteur juridique” (official responsible for legal drafting). According to a CNAVTS policy, any employee, after six months service, was automatically entitled to assessment of his/her performance in order to evaluate the possibility of promotion. T was on leave for over six months of the year because of both sickness and pregnancy and was denied assessment. However, had she not taken her maternity leave, she would have accumulated the required six months period necessary for the assessment. According to the relevant French legislation in force at that time, an employee was entitled to 16 weeks of maternity leave, which could be extended to 28 weeks, and that this period was “to be treated as period of actual work for the purpose of determining a worker’s rights by virtue of length of service” (L 123-1(c) Code du travail). T brought the case before the Conseil de Prud’hommes (Labor Tribunal) in Paris, which upheld her claim and ordered CNAVTS to compensate her. SNAVTS appealed to the Cour de Cassation (court of Cassation), which set aside the previous judgment and referred the case to the Conseil de Prud’hommes of Melun which reiterated the Paris tribunal’s conclusion. CNAVTS again appealed to the Cour de Cassation which referred the case to the ECJ. The ECJ held that the Equal Treatment Directive allows Member States to guarantee women specific rights on account of pregnancy and maternity. These rights are constructed so as to ensure the implementation of the principle of equal treatment between men and women. The Court stressed that, seen in this light, “the result pursued by the Directive is substantive, not formal equality”. The Court stated that Member States enjoy discretion on how to implement these rights; however, this discretion must be exercised within the boundaries prescribed by the Directive. Thibault marked the return of the pivotal principle that discrimination on grounds of pregnancy and maternity leads to direct discrimination which had been watered down since its establishment in Dekker.
Case C-136/95, Thibault  ECR I-2011
European Court of Justice