1 By interlocutory judgment of 4 December 1989, which was received at the Court on 15 December 1989, the Tribunal du travail, Nivelles ( Belgium ), Wavre Division, referred to the Court for a preliminary ruling under Article 177 of the EEC Treaty a question on the interpretation of Council Directive 79/7/EEC of 19 December 1978 on the progressive implementation of the principle of equal treatment for men and women in matters of social security ( Official Journal 1979 L 6, p . 24 ).
2 The question was raised in proceedings between Caisse d' assurances sociales pour travailleurs indépendants "Integrity", ASBL ( hereinafter referred to as "Integrity "), and Nadine Rouvroy, the widow of Jean Leloup, an architect, and her children, Olivier, Eric and Mathieu, concerning Mr Leloup' s social security contributions as a self-employed person, of which payment was sought for the years 1985 and 1986 .
3 Pursuant to Article 1 of Belgian Royal Decree No 38 of 27 July 1967 organizing social security for self-employed persons ( published in the Moniteur belge of 29.7.1967, p . 1001 ), its provisions extend to family benefits, retirement and survivors' benefits and sickness and invalidity benefits . It applies to self-employed persons and persons assisting them .
4 The first indent of Article 37(1 ) of the Royal Decree of 19 December 1967 ( published in the Moniteur belge of 28.12.1967, p . 1496 ), as amended by the Royal Decree of 20 July 1981 ( published in the Moniteur belge of 20.7.1981, p . 1218 ) laying down general rules for the implementation of Royal Decree No 38, provides : "When their income from employment within the meaning of Article 11(2 ) and ( 3 ) of Royal Decree No 38, on which the calculation of their contributions for a specific year is to be based, is less than BFR 77 472, married women, widows and students to whom Royal Decree No 38 applies may, for the year in question, apply to be treated as persons covered by Article 12(2 ) of that decree ."
5 Pursuant to Article 12(2 ) of Royal Decree No 38, a person to whom that decree applies, who, in addition to the activity giving rise to the application to him of the provisions governing self-employed persons, habitually engages in another occupation as a main occupation is not liable to pay contributions under Royal Decree No 38 if his income from working as a self-employed person remains below a specified ceiling . This exemption from contributions does not deprive the person concerned of the benefits available under the provisions applicable to self-employed persons .
6 In the proceedings before the Tribunal du travail, Nivelles, Mr Leloup, whose income was very modest, requested that Article 37 of the Royal Decree of 19 December 1967 be applied to him . Integrity contested that application on the ground that Article 37 applied only to married women, widows and students but not to married men and widowers . The heirs of Mr Leloup, who continued the proceedings after his death, maintained that Article 37 infringed the principle of equal treatment for men and women in matters of social security .
7 The Tribunal du travail, Nivelles, Wavre Division, stayed the proceedings and referred the following question to the Court for a preliminary ruling : "Does Article 37 of the Royal Decree of 19 December 1967 laying down general rules for the implementation of Royal Decree No 38 of 27 July 1967 organizing social security for self-employed persons comply with Directive 79/7/EEC of 19 December 1978 on the progressive implementation of the principle of equal treatment for men and women in matters of social security?"
8 Reference is made to the Report for the Hearing for a fuller account of the facts of the case, the course of the procedure and the written observations submitted to the Court, which are mentioned or referred to hereinafter only in so far as is necessary for the reasoning of the Court .
9 It must first be observed that although in proceedings under Article 177 of the Treaty, the Court may not rule as to the compatibility of national provisions with Community law, it is nevertheless competent to provide the national court with all the elements of interpretation under Community law to enable it to assess such compatibility for the purpose of deciding the case before it ( see most recently the judgment in Case C-196/89 Nespoli and Crippa [1990] ECR I-3647 ).
10 Directive 79/7/EEC is to apply, pursuant to Article 2, inter alia to self-employed persons . Article 3 lists the schemes and the provisions in respect of which the principle of equal treatment in matters of social security is to be implemented . Finally, pursuant to Article 4(1 ): "The principle of equal treatment means that there shall be no discrimination whatsoever on ground of sex either directly, or indirectly by reference in particular to marital or family status, in particular as concerns : ( i ) the scope of the schemes and the conditions of access thereto, ( ii ) the obligation to contribute and the calculation of contributions, ( iii ) the calculation of benefits including increases due in respect of a spouse and for dependants and the conditions governing the duration and retention of entitlement to benefits ."
11 It must therefore be concluded that the national court is asking, in particular, whether Article 4 of Directive 79/7/EEC must be interpreted as prohibiting a Member State from granting exclusively to married women, widows and students the possibility of being assimilated to persons who are not required to make any social security contribution where their income as self-employed persons is modest and where they habitually engage in another occupation as a main occupation .
12 The Court has consistently held ( see most recently the judgment in Case C-102/88 Ruzius-Wilbrink [1989] ECR 4311 ) that Article 4(1 ), standing by itself and seen in the light of the objective and content of that directive, is sufficiently precise to be relied upon by an individual before a national court in order to have any national provision not in conformity with that article declared inapplicable . It should be remembered in that regard that the directive requires the Member States to abolish any provisions which are contrary to the principle of equal treatment .
13 The Court also stated in its judgment in Ruzius-Wilbrink that, in a case of direct discrimination, the members of the group placed at a disadvantage are entitled to have the same rules applied to them as are applied to the members of the group placed at an advantage who are in the same circumstances, such rules remaining the only valid point of reference so long as the directive has not been implemented correctly .
14 Finally, it must be observed that, according to the internal logic of the directive, Article 4, which defines the extent of the principle of equal treatment, only applies within the scope rationae personae and rationae materiae of the directive ( judgment in Joined Cases 48, 106 and 107/88 J . G . Achterberg-te Riele and Others v Sociale Verzekeringsbank [1989] ECR 1963 ). In that connection, the Advocate General correctly observed in his Opinion that, where indivisible social security contributions relate to social security benefits which only partly come within the scope rationae materiae of Directive 79/7/EEC, the principle of equal treatment nevertheless applies to all such contributions . The position is different where it is possible to apportion the contributions among the individual benefits .
15 In view of all the foregoing considerations, it must be stated in reply to the question submitted by the Tribunal du travail, Nivelles, Wavre Division, that Article 4(1 ) of Council Directive 79/7/EEC of 19 December 1978 on the progressive implementation of the principle of equal treatment for men and women in matters of social security must be interpreted as precluding national legislation which reserves to married women, widows and students the possibility of being assimilated to persons not liable to pay any social security contributions without granting the same possibility of exemption from liability to pay contributions to married men or widowers who for the rest satisfy the same conditions .