Numerous lawsuits have been brought in France to engage the liability of manufacturers of medicines or vaccines on the grounds that they have caused a harm to the plaintiffs. One of the key issues that arises in these claims is to determine whether the disease has actually been caused by the litigious product.
The new vaccines against the Coronavirus, developed with a speed never known before, are already raising the question of the causation between the administration of a vaccine and the development of certain pathologies.
For example, French press has reported a criminal complaint that would have been filed in Dax in April 2021 by the family of a 70 years' old man who died, presumably of cardiorespiratory arrest, 12 days after receiving a dose of Pfizer vaccine.
It is therefore useful to make a review of the interpretation by French case law of the causation in medical matters.
1. The burden of the proof lies on the plaintiff
a. The plaintiff must evidence his/her exposure to the litigious product
Case law has consistently stated, in accordance with Articles 9 of the French Code of civil procedure and 1353 of the civil Code (formerly 1315) that it is up to the plaintiff who intends to hold liable the manufacturer of a vaccine or medicine to prove both his exposure to the product and the direct and certain causation between this exposure and his pathology.
The plaintiff's claim may therefore be dismissed if he does not demonstrate that he was exposed to the litigious product prior to the occurrence of the injury and that he 'has no other specific mode of contamination '.
In a decision of September 24, 2009 the Court of cassation (the French Supreme Court) uphold the judgment of a Court of Appeals which had judged that the proof of the plaintiff's mother's exposure to Distilbene could not be provided by 'affidavits from the plaintiff's memory, not supported by medical documents from the time of her pregnancy (...)'. In this case, the Court of Appeals had noted that the experts appointed by the first instance Court had concluded that the plaintiff's cancer could have several causes.
On September 24, 2009 also, the Court of cassation overturned a judgment that had dismissed the claims of a plaintiff who also suffered from cancer and whose mother had been exposed to Distilbene. In this case, the experts had attributed with certainty the plaintiff 's cancer to her mother exposure to Distilbene, which they considered the only possible cause of the plaintiff's cancer.
The manufacturer's liability was not upheld when the plaintiff did not precisely evidence the conditions in which the exposure to dioxin occurred and did not demonstrate a direct relationship between his disease and the presence of dioxin or herbicide in the environmentor did not show that the disorders mentioned in a medical certificate were caused by exposure to chemical products.
However, the mere proof of exposure to the product and of the occurrence of the disease is not sufficient to engage the liability of the manufacturer of the litigious product. It is still necessary to prove the causation between them. In a judgment of 21 June 2017, the Court of Justice of the European Union, seized by the French Court of cassation of a preliminary question on the interpretation of the Directive 85/374/EEC, recalled a basic rule of civil liability law, i.e. that:
2. Only in exceptional and very specific cases does French case law reverse the burden of proof
[N]ational courts (…) must ensure that the principle that it is for the victim to prove, through all means of proof generally allowed under national law and, as in the present case, inter alia through the production of serious, specific and consistent evidence, that there is a defect in the vaccine and a causal link, remains intact.
In the same judgment, the CJEU stated, in the field of product liability that:
However (…) evidentiary rules do not bring about a reversal of the burden of proof which, as provided for in Article 4 of Directive 85/374, it is for the victim to discharge, since that system places the burden on the victim to prove the various elements of his case which, where applicable, taken together will provide the court hearing the case with a basis for its conclusion as to the existence of a defect in the vaccine and a causal link between that defect and the damage suffered (see, by analogy, judgment of 20 November 2014, Novo Nordisk Pharma, C-310/13, EU:C:2014:2385, paragraphs 26 to 28).
Indeed, French case law reversed the burden of proof only in exceptional and very specific cases. In a case related to the liability of the blood transfusion center that provided the disputed transfusions, in a judgment of 9 May 2001, the Court of cassation has set three conditions for the transfusion center to have the burden of proving that the blood products are free of any defect. It must be shown that the plaintiff:
- Was exposed to blood transfusions prior to the viral contamination from which he/she is suffering,
- Has no other specific mode of contamination and,
- That the origin of the contamination cannot be found either in the plaintiff's lifestyle or history.
In a judgment of 24 September 2009 the Court of cassation has also exceptionally reversed the burden of proof by asking to each of the defendant laboratories to provide the negative proof, particularly difficult to establish, that its product was not the cause of the damage. But, in this case, the scientific causation between the product and the plaintiff's disease and the fault of the laboratories were established. The experts had 'stated without ambiguity that DES [diethylstimbestrol] was indeed the direct cause of the tumor pathology'.
Béatrice Parance noted that in this case:
[T]he Court of cassation recognized the lack of vigilance of the laboratories which had continued to market their product on French territory even though it had been banned in the United States
The question therefore remained as to which laboratory had manufactured the disputed molecule.
As Christopher Radé has rightly pointed out, transferring to the laboratories the burden of proof that it was not the incriminated molecule that they manufactured that caused the injury 'resembles a real sleight of hand'. This amounts to imposing on the manufacturer to provide a proof that it cannot provide since it is not the prescriber of the product.
1. The participation of the product in the occurrence of the damage must be evidenced in the first place
By application of the European Directive of 25 July 1985  the plaintiff must prove:
- The existence of a damage,
- The causation between the product and the damage,
- The defect of the product and,
- The causation between this defect and the damage.
The French Court of cassation specified in 2013 that:
[T]he participation of the product in the occurrence of the damage is an implicit prerequisite, necessary to exclude potential other possible causes of the disease, to search for the defect of the product and the causal role of this defect.
Thus, the plaintiff has to evidence that the disease is attributable to the litigious product. In a judgment of May 22, 2008 the Court of cassation confirmed that it was:
wrong [for the plaintiff to argue] that she did not have to establish the causation between her illness and the administration of the vaccine and that she only had to prove the defect in the product and then the causation between this defect and the damage.
Since she 'did not evidence the causation between the injection she received and the appearance of multiple sclerosis, [this] excluded the causation between the disease and the vaccination'.
The Court of cassation confirmed this ruling in 2011.
Recently, the Court of cassation recalled in the Lasso case involving the company Monsanto that, in order to engage the manufacturer's liability, 'the plaintiff must first establish that the damage is attributable to the product".
2. The existence of the defect and the causation between the product and the defect must also be evidence
If demonstrating the causation between the product and the occurrence of the damage is a necessary prerequisite, it is not sufficient to establish its defect.
In a judgment of January 24, 2006, the Court of cassation stated that the findings by the Court of Appeals that Guillain-Barré syndrome had occurred following the injection of the vaccine, that the vaccine had been the triggering factor of the disease, and that the marketing authorization listed this condition as an adverse effect, mentioning 'very rarely peripheral neuropathy', were insufficient to characterize the product's defect.
IV. The legal causation can be different from the scientific causation
Establishing a legal causation is easier when the adverse effect of a medicine or vaccine is scientifically established. When the scientific causation between a product and a pathology is not established, the question of the liability of the manufacturer of a medicine or a vaccine raises complex issues.
On this point, French case law has gone back and forth.
1. French case law ruled initially that legal causation is not established in the absence of scientific certainty
Initially, particularly in cases concerning vaccination against hepatitis B and the occurrence of multiple sclerosis, the Court of cassation ruled that the defect in the vaccine and the causation between the vaccination and the disease could not be established in the absence of scientific certainty as to the etiology of the multiple sclerosis, even when the Court of Appeals had noted that the patient:
was in perfect health before the first injection of the vaccine, that there was a concordance between the vaccination and the onset of the disease, which had also been observed in other patients, and that there was (...) no other cause for the onset of the disease.
2. French case law evolved by resorting to presumptions to establish legal causation in the absence of scientific certainty
French case law then evolved by resorting to presumptions, which must be, on the basis of former Article 1353 of the civil Code, and as of 10 February 2016, of Article 1382 of the same Code, serious, precise and corroborative.
But this has opened a Pandora's box and led to discrepancies in the decisions of lower Courts and even between certain judgments of the Court of cassation.
Luc Grynbaum noted that:
[T]he attention paid in the hepatitis B vaccine litigation to proving the causation by presumptions has obscured the question of the defect (...). We have witnessed (...) a shift from the question of evidence of the causation to an irrebuttable presumption of defect in this health product. This is regrettable if one keeps to the legal rigor of the reasoning.
In 2006, the Court of Cassation expressly relied on the existence of serious, precise and corroborative presumptions of the causation between Creutzfeldt-Jakob disease and the growth hormone supplied by the France Hypophyse association.
In this case, this presumption was practically a certainty since the Court of Appeals had retained that all the patients treated with growth hormone who had developed Creutzfeldt Jakob disease had received the growth hormone supplied by the France Hypophyse association. Moreover, the fault of the laboratory had been demonstrated. Indeed, the lack of care and diligence of the Pasteur Institute, which had not taken the necessary precautions in the extraction, purification and composition of the growth hormones and which had continued the treatment by extractive hormone in common agreement with the France Hypophyse association, despite the recommendations that had been provided, had been established.
Judgments handed down by the Court of cassation on 22 May 2008 criticized the Courts of Appeals for having adopted:
a probabilistic approach deduced exclusively from the absence of a scientific and statistical link between vaccination and the development of the disease, without investigating whether or not the evidence submitted to it constituted serious, precise and corroborative presumptions of the defective nature of the vaccine at issue, as well as of the causation between a possible defect and the harm suffered.
However, a certain drift has been noted since in 2009, the Court of cassation went so far as to overturn a decision that had dismissed the laboratory's liability when there was no formal evidence of a direct and certain causation between the injections of the vaccine and the onset of the plaintiff's neurological condition. The Court of cassation criticized the Court of Appeals for having excluded the laboratory's liability, even though the experts had not excluded the hypothesis of a correlation. According to the Court of cassation; the Court of Appeals should have taken into account the probability of a causation and determine whether there was a presumption of causation, as in that case:
the absence in the family history and antecedents of elements, likely to suggest a neurological disease, militated in favor of a probable causation between the injection of the vaccine and [the plaintiff's] sudden pathology.
Yet, Jean-Sébastien Borghetti rightly asked:
How can one be persuaded by a decision that a medicine caused a disease in a particular case, when the medical and scientific evidence does not generally link this medicine to that condition?
Indeed, the simple criterion of probability, of possibility, seems contrary to the notion of evidence. It was on the basis of a hypothetical reasoning that the Court of cassation also in 2009, confirmed an appeal decision that had held the vaccine manufacturer liable, on the ground that although the scientific studies:
did not reveal a statistically significant increase in the risk of multiple sclerosis or demyelination after vaccination against hepatitis B, they did not exclude a possible link between this vaccination and the occurrence of multiple sclerosis-type demyelination.
According to the Court of cassation, the 'possible' link was established since the first manifestations of multiple sclerosis had occurred less than two months after the last injection, that there was no neurological history in the family and that thus 'no other cause could explain this disease.
However, it should be added that on the contrary an appeal decision that had found a causation between multiple sclerosis and the hepatitis B vaccination, was overturned in 2010 by the Court of cassation which ruled that:
[I]n the absence of a scientific consensus in favour of a causation between vaccination and demyelinating diseases, the fact that Mrs. G had no personal or family history and the fact that the first symptoms appeared fifteen days after the last injection did not constitute serious, precise and corroborative presumptions.
It can be seen from the above that this case-by-case case law can be very different depending on the Court seized and has created a harmful legal uncertainty.3. The determination of the existence of presumptions combines an assessment in abstracto and in concreto
In 2013, the Court of Cassation approved in an unusually detailed manner, the criteria used by a Court of Appeals to find that there was no sufficient element to conclude that there were serious, precise and corroborative presumptions based on:
- An assessment in abstracto which could correspond to the concept of general causation in American law:
- The experts are almost unanimous in concluding that a causation between vaccination and multiple sclerosis cannot be demonstrated;
- Statistical data have not shown an alarming spike in reports of multiple sclerosis over four years of vaccination despite the very high number of doses administered. Thus, the positive benefit/risk ratio is such as to exclude the correlation between vaccination and the occurrence of the disease;
- The appearance of the disease concerned at 17 years of age is not exceptional;
- The diagnosis several years after vaccination and the absence of previous manifestations of the disease and of any other possible cause are the lot of many other persons suffering from multiple sclerosis without having been vaccinated,
- The manifestations alleged by the plaintiff after the injections were based solely on her statements;
- The diagnosis two years after the vaccination and the absence of previous manifestations of the disease and of any other possible cause were not evidentiary enough, as the negative facts could not establish the evidence.
[T]he benefit expected from the hepatitis B vaccine by its user is above all an effective protection against this virus, which is the case, which is why the of 21 June 2017hepatitis B vaccine, which has probably saved thousands of lives for which the risk of hepatitis B was infinitely greater than the risk of multiple sclerosis, has not been withdrawn from the market and has received the required authorisations up to the present day, and that if the Ministry of Health has put an end to systematic vaccination campaigns, this reservation cannot contribute to establishing the defective nature of the product.
According to the Court of cassation, the Court of Appeals could not ground its decision on a general consideration of the benefit/risk ratio of the vaccination without having examined the specific causation, i.e. whether there were no serious, precise and corroborative presumptions that the product was defective and caused the disease.
V. Recent case law appear to return to a stricter interpretation of causation
1. The CJEU interpretation of the directive 5/374/EEC on causation and presumptions
In its judgment of 21 June 2017, the CJEU stated that:
[A] court ruling on the merits of an action involving the liability of the producer of a vaccine due to an alleged defect in that vaccine, in the exercise of its exclusive jurisdiction to appraise the facts, may consider that, notwithstanding the finding that medical research neither establishes nor rules out the existence of a link between the administering of the vaccine and the occurrence of the victim’s disease, certain factual evidence relied on by the applicant constitutes serious, specific and consistent evidence enabling it to conclude that there is a defect in the vaccine and that there is a causal link between that defect and that disease.
Thus, when there is a scientific uncertainty, the causation must be assessed on a case-by-case basis and may be established in particular by the production of serious, precise and corroborative clues.
But the CJEU also rejected the possibility of an automatic presumption. It specified that Article 4 of the Directive precluded evidentiary rules based on presumptions according to which:
the existence of a causal link between the defect attributed to the vaccine and the damage suffered by the victim will always be considered to be established when certain predetermined causation-related factual evidence is presented.
Indeed, an irrebuttable presumption of causation would be particularly objectionable and paradoxical when there is no scientific certainty about the existence of the causation.
2. The application by the court of cassation of the CJEU interpretation of causation and presumptions
Following the CJEU ruling, as of 2017, the Court of cassation returned to a stricter assessment of the causation and cited in its judgments the warning of the European Court against an interpretation by the national judge:
which would in practice amount to establishing, to the detriment of the producer, forms of unjustified presumptions that would be likely to infringe Article 4 of Directive 85/374, or even to undermine the very effectiveness of the substantive rules laid down in that directive,
and against an 'unduly undemanding' application of the evidentiary regime 'by being satisfied with irrelevant or insufficient evidence'.
Indeed, the Court of cassation upheld, in its judgments of October 18, 2017 and December 20, 2017 the judgments of the Paris Court of Appeals, which had ruled that
- The absence of personal and family risk and possible other causes of the disease in the plaintiff 'as 92 to 95% of patients with multiple sclerosis have no antecedents of this nature',
- The rarity of the occurrence of multiple sclerosis in children or in the population to which the plaintiff belonged,
- The criterion of the proximity in time between the appearance of the first symptoms and the vaccination of the plaintiff,
- The ignorance of the etiology of multiple sclerosis,
were not sufficient to retain the existence of serious, precise and corroborative presumptions allowing to conclude that there is a causation between the multiple sclerosis from which the plaintiff suffered and her vaccination against hepatitis B.
In a statement of principles, the Court of cassation stated, in its judgment of December 20, 2017, that the lower Courts must assess the value and scope of the evidence submitted to them in favour of the existence of a causation between the disease and the vaccination without determining themselves on hypothetical grounds.
In one of its 2017 judgments, the High Court thus upheld the judgment of a Court of Appeals which had found that:
[T]he serious doubts expressed by certain experts as to the existence of a causation between the vaccine and the disease cannot constitute a presumption, since the defect in a vaccine cannot be deduced from the absence of scientific certainty of the product's harmlessness.
Therefore, according to the Court of Cassation, scientific uncertainty is not per se a presumption of a defect of the product and of the manufacturer's liability.
3. Recent case law seems to apply a strict interpretation of the presumptions of causation between a disease and a product
Even in the Mediator case, the manufacturer's liability was not engaged if it was not demonstrated that a pulmonary hypertension observed three years after stopping this medecine and occurring in a context of pulmonary fibrosis, was directly and definitely linked to the use of Mediator.
In 2020, the Versailles Court of Appeals judged that it is not possible to retain the existence of 'serious, precise and corroborative clues allowing one to consider as acquired a direct link between the surgical act and an infection' when there are several risk factors predisposing to infectious phenomena, i.e. in this case a history of diabetes and very significant obesity.
In 2021, the Lyons Court of Appeals judged that the legal causation was not established:
in an undisputed context where the scientific community agrees that the causation between multiple sclerosis and the vaccine has not been demonstrated and where the etiology of multiple sclerosis is still unknown to-day.
It found that there were no serious, precise and corroborative presumptions of a causation between multiple sclerosis and the hepatitis B vaccination when the first symptoms were noted three years after the injection, the testimonies came essentially from the family and referred to subjective and long-standing considerations, and that only one medical certificate drawn up 24 years after the vaccination was produced.
Recent judgments seem more reluctant to consider that suspicion and hypotheses can form the basis of a serious, precise and corroborative presumption. Thus, the Montpellier Court of Appeals ruled that 'mere suspicion cannot suffice to establish the defect' of the product.
In this case, it was more than three months after the implant that the tinnitus had appeared, and the known complications of pain in the surgical area and the tinnitus were already present in the patient before the operation. The Court held that the suspicion of malfunction noted by the expert was not sufficient to engage the manufacturer's liability.
It was also judged that the serious, precise and corroborative presumptions of a causation between the plaintiff's disease and his vaccination were not established, when 'the diagnosis of post-vaccination encephalitis could be considered as suspicious, but could not be retained as probable (...) nor certain'.
Similarly, the mere fact that diseases were caused by massive exposures to Lindane does not allow to conclude that this product caused the plaintiff's disease when he had handled several solvents that aggravate the toxicity of Lindane and that none of the doctors had concluded that there would be a direct, certain and exclusive causation between an exposure to Lindane and the plaintiff's disorders.
Even if one of the experts argued that there would be a very strong suspicion that there is a link between an exposure to Lindane and kidney cancer, since the results of the scientific literature are discordant on a causation between this product and this disease, and studies conclude that this type of exposure cannot be directly and essentially responsible for the occurrence of kidney cancer, the plaintiff's exposure to the product cannot be presumed to have favored the appearance of kidney cancer.
In the cases relating to Distilbene, if it contributed in a certain way to the occurrence of certain pathologies suffered by the plaintiff, the causation is retained. But the involvement of Distilbene in the occurrence of ectopic pregnancies and secondary infertility mentioned in the experts' report is not retained if it is based on a hypothesis. The same applies to the plaintiff's early miscarriages if they are only slightly higher than in the general population.
The return of case law in recent years to a more rigorous interpretation of the causation may make it possible to overcome the sometimes confusing contradictions that have been noted between French courts decisions because of an overly broad admission of presumptions in cases of scientific uncertainty. One may also wonder whether the Courts judgments that have widely accepted the existence of a causation between the injection of a vaccine and the occurrence of a disease in the absence of scientific certainty have not inadvertently fuelled the vaccine scepticism of some parts of the population across the world.
Article first published in EPLR - European Pharmaceutical Law Review
 'Each party has the burden of proving in accordance with the law the facts necessary for the success of its claim'.
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