The establishment by the Court of Cassation of the principle of the unity of illegality and fault in the context of a liability action against a public body for its illegal decision.
Luxembourg law governing civil liability finds itself at the crossroads of the influences of French and Belgian law, both of which present numerous divergences not only in terms of the distribution of competences between the different courts but also in respect to the rules themselves. This setting is not without impact, quite the contrary: the specificity of Luxembourg law is reflected in the elegant synthesis that it has been able to achieve of the two aforementioned systems.
The present article therefore aims to present, in a synthetic manner, its legal specificities in the field of civil liability, both at the jurisdictional level and as regards the rules governing the action in civil liability. With regard to the latter, the scope of the article shall be limited to that of the Cour de cassation's ruling and will envisage the specific hypothesis whereby the State issues an administrative decision that is subsequently ruled illegal by a court.
II. Brief overview of the Luxembourg jurisdictional organisation in the context of a civil liability claim brought against a public body
While since the Blanco judgment of 8 February 1873 by the Tribunal des Conflits, the liability of public authorities has been governed by a different and autonomous regime from that applicable in private matters and falls within the exclusive jurisdiction of the administrative courts in the French legal system, the Luxembourg Constitution, modelled on the Belgian one, grants jurisdiction to the judicial courts in respect of civil rights. Indeed, it should be noted that the jurisdiction of the courts in Luxembourg law is not determined by the quality of the subject of the law, but by the object of the action brought by the subject.
As such, a civil liability claim, whether directed against a private entity or a public body, shall always be the subject of the sovereign and exclusive appreciation of the judicial courts. However, matters become more complicated depending on the nature of the faults that the State, in its various forms, is likely to commit. Indeed, such is the case whereby a public body adopts a decision that is prejudicial to the rights of a given individual or group of individuals. It thus follows that, as a result of the jurisdictional architecture, the victim of the said decision is required to proceed in two stages: firstly, it is necessary to obtain the annulment of the decision before the administrative courts, before bringing, in a second phase, a civil claim in order to obtain reparation of the damages incurred as a result of the decision.
III. As regards the legal grounds for a civil liability claim
Traditionally, the liability of public authorities was governed exclusively by the provisions of the Civil Code, namely by articles 1382 to 1386, of which one of the most important is article 1382, which establishes the fault-based liability regime.
Although the necessary conditions to be met both in the case of a civil liability action against a private law person are the same as those against a public law legal person, the approach of the courts were divergent. Indeed, if the Luxembourg courts had no difficulty in making private individuals liable for "all errors of law" they would commit, the position with regard to the administration was not the same. The core of the debate revolved around the question whether an administrative act adopted by a public authority which is subsequently declared illegal by the administrative courts could be considered a fault for which the administration should be held responsible.
Until now, the position of the Cour de cassation in this matter has been expressed firmly and unequivocally in a judgment of 24 November 1977, in which it considered that not only does the annulment by the Council of Stateof an administrative decision not necessarily express a wrongful character of this decision, but also that it would be excessive to make the Administration responsible for all the errors of law that it makes. This decision was supported by a lengthy argument, which expressed the difficulty of making the administration or its body liable, given that the error had to be obvious and certain that an informed person placed in the same circumstances as the administrative authority would not also have committed it, and that there is nothing to suggest that the incorrect interpretation or application is the result of a light-hearted consideration of the matter or a lack of professional conscience.
It is important to note that Luxembourg case law has already evolved in the meantime in a direction contrary to the solutions advocated by the 1977 judgment. Indeed, from the 1980s onwards, despite the recent ruling of the Cour de cassation expressing the opposite view, Luxembourg case law began to enshrine the principle of the unity of illegality and fault under the influence of the evolution of French and Belgian case law.
Lastly, a notable development in this area was the adoption of the Act of 1 September 1988, which, according to the parliamentary debates, sought to guarantee better protection for citizens who are victims of the “defective functioning of public services”. Paragraph 1 of article 1 of the said law provides that : “The State and other legal persons governed by public law shall be liable, each within the framework of its public service missions, for any damage caused by the defective operation of their services, whether administrative or judicial, subject to the authority of res judicata.”. At the time of the parliamentary debates, the judicial commission noted in its report that, although the case law should be praised for evolving in favour of the victim, – by consecrating the principle of the unity of illegality and fault-, it feared that, without a legal text, this approach could be abandoned at any given time and courts may choose to rally again to the position expressed by the Cour de cassation in its 1977 ruling.
As such, according to the report drafted by the judicial commission, the intention of the legislator was to enshrine in law the principle of the unity of illegality and fault by allowing the individual to engage the responsibility of the State on the basis not of a fault, but of that of a simple faulty functioning of the service. Surprisingly, although the case law has followed the trend in favour of the unity of illegality and fault, the courts have refused to distinguish between the defective functioning of the service within the meaning of Article 1(1) of the 1988 Act and fault within the meaning of Article 1382 of the Civil Code.
IV. As to the scope and merits of the recent ruling of the Cour de cassation
The case in question bears great resemblance to that of a textbook case: a company was refused permission to reallocate part of a building belonging to it. The decision of the public body was swiftly challenged before the Administrative Court. The latter having granted its request, the company then brought an action before the judicial courts to have the administration in question held liable on the basis of article 1, paragraph 1, of the law of 1 September 1988. The judicial courts ruled in its favour and an appeal was subsequently lodged by the public body. However, the appeal did not succeed, as the Court of Appeal considered that the theory of unity of the concepts of fault and illegality has the value of a general principle of law, so that a simple error of assessment or interpretation by the public body justifies it being sentenced on the basis of article 1, paragraph 1, of the law of 1 September 1988 relating to the civil liability of the State and public authorities.
The administrative authority appealed before the Cour de cassation (= Supreme Court, only reviewing issues of law), arguing that such a general principle of law does not exist and cannot in any case be based on paragraph 1, article 1 of the law of 1 September 1988. On the contrary, in its view, such a principle of law violates the wording and the spirit of the said article, insofar as the text does not in any way imply it.
It is in this context that the Cour de cassation decided to make a reversal of its 1977 case law, considering that : "While it is true that the principle of unity of fault and illegality is not formally enshrined in the law of 1 September 1988 on the responsibility of the State and public authorities, the fact remains that by enacting Article 1 of the 1988 law in the version recommended by the Ministry of Justice and the Legal Committee, the legislator intended to enshrine the theory of unity of the concepts of illegality and fault in order to guarantee better protection for citizens who are victims of the defective operation of public services, the judges of appeal held that it was established, in view of the illegality of the administrative act, found by the administrative court, that the applicant's services had functioned in a defective manner and therefore did not violate the provision referred to in the plea”.
Not only does the ruling consecrate the 1988 Act as the legal basis for the theory of the unity of illegality and fault, but it also radically shifts the paradigm by breaking off from the previously unanimously held view. Indeed, it seems that the Belgian, French and now Luxembourgish courts no longer see any serious reason to depart from the principle of equal treatment between the individual and the public body and to render more difficult a civil liability claim brought forward by the former, who already experiences far more difficulty in knowing and applying the law correctly than the latter.
It follows that, in full compliance with the intention expressed in a rather subtle way by the legislator when adopting the 1988 law, the condition of the victim has been improved. Of course, the victim is still required to prove a loss and an uninterrupted chain of causation between the said illegality and the loss suffered, which is not without difficulty, but it can be argued that the difficulty of proving a fault on the part of the public body has been considerably reduced.
Finally, the present ruling also puts an end to the dialogue between Belgian, French and Luxembourg case law and confirms, all the while bringing a much-needed dose of legal certainty, the defiant direction taken by the lower Luxembourg courts from the 1980s onwards.
 Hereafter used interchangeably with the terms “public body” and/or “administrative authority”
 Georges RAVARANI, La responsabilité civile des personnes privées et publiques, 3ème édition 2014, page 223
 Former supreme court in administrative matters, now replaced by the Administrative Court of Appeal
 As noted by the Court of Appeal in the judgment which is the subject of this appeal, page 5, fourth paragraph.
 In the original French version, the law states that : « L´Etat et les autres personnes morales de droit public répondent, chacun dans le cadre de ses missions de service public, de tout dommage causé par le fonctionnement défectueux de leurs services, tant administratifs que judiciaires, sous réserve de l´autorité de la chose jugée. »
 Rapport de la Commission juridique, du 1er juillet 1988 (Document parlementaire n° 2665-7), p. 3, dernier alinéa
 Solely the answer given by the Cour de cassation to the first plea of the plaintiff in cassation in its three branches shall be discussed.
 In the original version : « s’il est vrai que le principe d’unité de faute et d’illégalité n’est pas consacré formellement dans la loi du 1er septembre 1988 relative à la responsabilité de l’Etat et des collectivités publiques, il n’en reste pas moins qu’en édictant l’article 1er de la loi de 1988 dans sa version préconisée par le ministère de la Justice et la commission juridique, le législateur e entendu consacrer la théorie de l’unité des notions d’illégalité et de faute afin de garantir une meilleure protection des administrés victimes d’un fonctionnement défectueux des services publics, les juges d’appel ont retenu qu’il était établi, au regard de l’illégalité de l’acte administratif, constatée par le tribunal administratif, que les services de la demanderesse en cassation avaient fonctionné de manière défectueuse et n’ont partant pas violé la disposition visée au moyen. »