I Facts

How to prove that a vaccine has caused a serious side-effect when there is no conclusive medical research? This is the question that the Court of Justice of the European Union (CJEU) is required to answer in this case. The preliminary question formulated in W and Others was requested by the French Cour de cassation as a result of the appeal brought by W and others before that national court.Footnote ¹

The case concerns Mr W, who was vaccinated against hepatitis B between 1998 and 1999. The vaccine injected was produced by Sanofi Pasteur. Following the third and final injection, Mr W was diagnosed with multiple sclerosis, which led, in October 2011, to his death.

In 2006, three members of Mr W’s family brought proceedings against Sanofi Pasteur. They asked the regional court of Nanterre to order Sanofi to pay compensation for the damage suffered due to Mr W’s vaccination. The plaintiffs contended that “the short period between the vaccination and the appearance of the first symptoms of multiple sclerosis, in conjunction with the lack of any personal or family history of disease, are such as to give rise to serious, specific and consistent presumptions as to the existence of a defect in the vaccine and as to there being a causal link between the injection of the vaccine and the occurrence of the multiple sclerosis”.Footnote ²

Several court cases followed, leading to an appeal before the Cour de cassation. At this stage, the court decided to stay the proceedings and to refer a number of questions to the CJEU.

The questions concern the Product Liability DirectiveFootnote ³ and, more specifically, the interpretation of Article 4. This provision states that, in the case of a defective product, “the injured person shall be required to prove the damage, the defect and the causal relationship between defect and damage”. The national court asked whether, when medical research does not establish a relationship between a vaccine and the occurrence of a disease, the court can infer from the specific facts that the vaccine was indeed defective and that a causal relationship could be established.

II Judgment

The CJEU first acknowledges that, for the producer’s liability to be established, Article 4 of the Product Liability Directive requires the injured person to prove the causal relationship between the defect of a product and the damage. However, the Directive does not define the concept of “causal relationship”, nor does it define the ways in which such proof needs to be established. Accordingly, it is for the national legal order of each Member State to develop the principles concerning the provision of evidence.Footnote ⁴

In light of such national autonomy, the Court then assesses whether the system established in France is compatible with the Product Liability Directive.Footnote ⁵ The essential element is whether national rules are drafted in such a way that they reverse the burden of proof so that it is not for the victim to prove the causal relationship but for the producer to refute the victim’s assertion. This would be incompatible with the system established in the Directive.

The French evidentiary rules “make it easier for the victim to provide the requisite evidence enabling him to establish liability on the part of the producer”.Footnote ⁶ Indeed, the system allows the victim to conclude that there has been a defect when the evidence is serious, specific and consistent enough to consider, “with a sufficiently high degree of probability” that the causal relationship exists.Footnote ⁷

However, the Court does not consider this system to be incompatible with the Directive. First, it does not imply a reversal of the burden of proof because it will still be for the victim to prove that various elements are met which, taken together, allow a conclusion to be made on the damage and the causal relationship.Footnote ⁸ Second, the Court states that rules impeding any recourse to circumstantial methods and obliging the victim to prove the damage exclusively on the basis of medical research would actually be contrary to the Product Liability Directive.Footnote ⁹ It would make it “excessively difficult in many situations or, as in the present case, where it is common ground that medical research neither confirms nor rules out the existence of such a causal link, impossible to establish producer liability”.Footnote ¹⁰ The objectives and the effectiveness of the Directive would therefore be put at risk under such an interpretation.

While the Court seems to be somehow lenient in the first part of its judgment, it then goes on to discuss the limits to the evidentiary rules that can be established by national legal orders. It states that national rules “must not be applied by the national courts in such a way that in practice they introduce, to the detriment of the producer, unjustified presumptions liable to infringe Article 4 of Directive 85/374 or even undermine the very effectiveness of the substantive rules laid down by the directive”.Footnote ¹¹ The Court gives two examples of this statement. First, national courts cannot accept irrelevant or insufficient evidence; second, they cannot apply the presumption in an immediate and automatic way as soon as one or more pieces of factual evidence are presented together.Footnote ¹² Accordingly, it is essential that the burden of proof is not disregarded and that the effectiveness of the system is ensured in all cases.

The Court then analyses the above-mentioned principles in the specific circumstances of the case. The fact that the disease occurred very shortly after the vaccine had been administered, that there was no personal or familiar history of the disease and that there have been other similar cases reported are considered by the Court as constituting evidence that could lead the national court to consider that the victim’s burden of proof has been complied with.Footnote ¹³

However, the Court rules that such an evidentiary system must apply on a case-by-case basis. As a consequence, it cannot be established that certain pre-determined facts will always prove a causal link. According to the Court, such reasoning would imply that certain irrefutable presumptions regarding causal links exist, and this would compromise the effectiveness of the system of liability as established in the Product Liability Directive.Footnote ¹⁴ Even if such presumptions were refutable, the CJEU is of the opinion that this line of reasoning would automatically put the producer in the position of having to defend itself against the claim, thus reversing the burden of proof.Footnote ¹⁵

Consequently, the CJEU concludes that evidentiary rules such as those established in the French legal system are compatible with Article 4 of Directive 85/374 but that they must apply on an individual basis after a careful assessment of the particular circumstances of the case.

III Comment

This judgment provides an interesting reading of Article 4 of the Product Liability Directive and will undoubtedly bring some clarity to the interpretation of this provision. This is particularly welcome considering that the Directive has been criticised on account of its lack of detail.Footnote ¹⁶ Such lack of clarity can be explained by the opposition that the drafters of this legislative text found during the whole adoption process. Not only was the business sector afraid that claims and lawsuits would dramatically increase as a result of the new Directive, but the European Parliament and the Council were also very sceptical as they considered that the system of liability imposed by the text was too strict.Footnote ¹⁷ Consequently, the result of the legislative procedure, which lasted for more than ten years, was a complex and vague instrument that is often difficult to understand.

However, the interpretation of the Product Liability Directive has not been made any easier ever since, neither from a legislative perspective, nor from a judicial one.Footnote ¹⁸ From a legislative perspective, the European Commission has not been willing to reform the text. Although it is acknowledged that the Directive is not always properly implemented, the Commission always concludes that no legislative reform is necessary.Footnote ¹⁹ This is surprising due to the number of cases that have been brought before the CJEU on the failure of Member States to properly transpose or implement the Directive, particularly concerning France.Footnote ²⁰ From a judicial perspective, the CJEU has not been able to help either with the interpretation of this text because very few cases concerning the substantive interpretation of the Directive have been brought before it.Footnote ²¹ Such cases might have provided the Court a mechanism to clarify the meaning of some provisions, thus allowing for the homogenisation of national legislation.Footnote ²² Accordingly, the judgment of the Court in W and others may be of great value and should be carefully considered.

In more specific terms, W and others raises interesting issues regarding the burden of proof under Article 4 of Directive 85/374. This is of particular relevance considering the observations of the European Commission on this specific provision in its latest report on the application of the Directive.Footnote ²³ It was acknowledged in 2011 that considerable differences existed amongst Member States regarding the burden of proof. It was also stated that victims faced difficulties in proving that damage had been caused by a product’s defect. More specifically, the difficulties were related to “the costs involved in obtaining an expert opinion” and “the economic costs of furnishing proof of the defect of certain highly technical products”.Footnote ²⁴ Some Member States had, accordingly, asked for the amendment of this provision. In this context, a presumption of liability or a mechanism to reverse the burden of proof in some circumstances had been proposed.Footnote ²⁵

In W and Others, the CJEU could be considered to have taken the opportunity to address such difficulties. The Court takes into account the solutions proposed in the European Commission’s Communication while considering the producers’ interests. It adopts a balanced position according to which Member States can freely choose their evidentiary rules, such rules can be based on presumptions, but presumptions need to be refutable and have to be analysed on a case-by-case basis. While it has been stated that this preliminary ruling “leaves the pharmaceutical sector more vulnerable to product liability claims”,Footnote ²⁶ the truth is that the Court does take all interests into account. As Advocate General Bobek specifies in his Opinion, national rules such as the French ones in W and others might have the purpose of redressing the information asymmetry that exists between the consumer and the producer, particularly in highly technical areas such as the pharmaceutical sector.Footnote ²⁷ Moreover, a different solution would mean that, when no medical research is available, patients would not have any resource at their disposal to prove that a medical product is defective and that a side-effect has occurred as a consequence of it. This could not only make it impossible to establish the producer’s liability in some cases,Footnote ²⁸ but it could also eventually be taken advantage of by the pharmaceutical industry. It would be easier for the sector not to invest in medical research if, by doing that, patients are not able to claim liability in case of a side-effect. Accordingly, the possibility to rely on evidentiary rules such as those specified in this case appears to be an acceptable compromise considering that the presumptions are rebuttable.

Lastly, it is interesting to note that, while the Court in a preliminary ruling should only answer the questions of a national court on the interpretation (or the validity) of EU law, it goes one step further in this judgment and applies the principles established to the particular case.Footnote ²⁹ While this can be seen as the Court overstepping its competences,Footnote ³⁰ it can also be interpreted as a desire to guide national courts through a legislative text often considered to be excessively difficult to interpret. Accordingly, it is argued that the detailed analysis of the Court in this judgment will contribute to the uniform interpretation of this difficult text amongst Member States.

All in all, this judgment should be mostly welcome both by practitioners and by patients. It increases the legal certainty of the Directive by clarifying the meaning of its provisions and it allows national legal orders to increase the available tools that patients can have at their disposal to claim damages, while protecting the effectiveness of the Product Liability Directive.