Over the last few decades, the multiplication of scandals related to health products has spurred legal professionals to adopt a dynamic interpretation of product liability based on the law of 19 May 1998.
Liability for defective health products, which establishes strict liability for laboratories, may be perceived in this respect as a favorable regime for victims. However, the difficulty of providing evidence in order to implement this liability weighs on the victims (I) and has consequences (II).

I. The conditions for implementing product liability

Two legal difficulties arise in order to engage the liability of laboratories. The victim must prove the defectiveness of the health product (A) and the existence of a causal link (B).

A. The defective nature of the health product

The defect of the product is proof of the operative event of the producer or manufacturer of the health product’s strict liability. In this sense, article 1245-9 of the Civil Code provides that "the producer may be liable for the defect even though the product was manufactured in accordance with the state of the art or existing standards or was the subject of an administrative authorization". In the vast majority of cases, it involves the manufacturers, but it is difficult to prove until a scandal breaks out and puts an end to this omerta. The defective nature of the product is assessed on a case-by-case basis and is determined according to the safety that the victim can legitimately expect. Such is for example the case of Depakine in the decision of the 1st civil chamber of the Court of Cassation dated November 27, 2019 by which the High Court ruled that the respect of minimum safety standards by the producer was insufficient with regard to legitimate expectations since the latter must not be satisfied with it. In this case, the leaflet of Depakine, intended for patients, did not indicate the risks of malformation of the newborn in case of taking during pregnancy. Consequently, the product's defectiveness can be assessed in relation to the lack of information on the serious risks in the package insert, even though the producer was aware of these risks at the time of the marketing authorization - recorded in the 2001 edition of Vidal. Therefore, the lack of safety of the medicine is characterized.
Thus, under the provisions of Article 1245 of the Civil Code, damages caused by a product defect -vaccines, drugs, prostheses- engage the strict liability of the producer, i.e. the laboratories, even if they are not bound by a contract with the victim. However, financial guarantees may be granted regarding the product's defect if the laboratories have demonstrated transparency and if scientific advances are not sufficient to ensure the absence of side effects. This is the case for the COVID-19 vaccine, because of its fast production - one year instead of ten years - caused by the unprecedented nature of the pandemic and the need to protect the population. In this particular case, the laboratories, under the aegis of European Union law, through the clause stipulated in the advance purchase contracts with the EU Member States, are exempted from compensation, which is the responsibility of the State.
However, in order to hold laboratories liable for a defective health product, proof of the defect is only the premise of this liability action. The victim must also demonstrate the existence of a causal link between the damage and the administration of the product, as well as between the defect and the damage.

B. The existence of a causal link

The causal link is particularly difficult to establish, in particular because the effects of a drug's defect may be multiple. Nevertheless, it is settled case law, since a decision of the 1st civil chamber of the Court of Cassation of May 22, 2008, affirmed by the Court of Justice of the European Union in a decision of 2017, that if there is no consensus within the scientific community as to the defect of a health product and the causal link between the said product and the damage as well as its exposure, the proof can be brought by a group of serious, precise and concordant body of evidence. Therefore, scientific uncertainty is not an obstacle to prove the double condition.
Proof of exposure to the health product can be provided in several ways, depending on whether the etiology is unique or multifactorial. In the case of a single etiology, such as clear cell adenocarcinoma, which is specific to Distilbene exposure, there is a reversal of the burden of proof, due to the simple presumption of exposure of the victim to Distilbene, which is now incumbent on the laboratories. On the other hand, in cases where it is not certain that the health product is the only possible cause of the damage, the burden of proof of exposure to the product, as well as its imputability to the damage, to establish the causal link remains with the victim. But the 1st civil chamber of the Court of Cassation, by a decision dated June 19, 2019, which is in line with the jurisprudential trend, affirms the possibility of resorting to the presumptions of the human fact, that is say to the appreciation of the lower courts. However, this sovereign appreciation is tempered since the judges of the High Court can make a control of motivation, although as a general rule they refuse to appreciate the body of evidence contrary to the administrative judge.
As regards the imputability of the damage to the health product, this can be established by any means, by serious, precise and concordant presumptions as mentioned above, but it remains "an ambiguous notion, with fluctuating contours", a source of legal difficulties as early as the case concerning the hepatitis B vaccine. Indeed, imputability can be understood in two ways. It may refer to the doctrinal concept of scientific causality requiring direct proof, or to the notion of imputation of the damage to one of the causes of exposure.

Consequently, the implementation of health product liability entails consequences.

II. The consequences of health product liability

The system of strict liability of the producer presents difficulties for victims - apart from the ten-year time limit - such as the exemption of laboratories from liability for developmental risks (A). Nevertheless, the victims of damage caused by a health product are entitled to compensation, whether or not the producer is liable (B).

A. The cause of exoneration for developmental risk

The doctrine defines the risk of development as "the defect in a product that the producer was unable to discover or avoid, because the state of scientific and technical knowledge at the time the product was put into circulation did not allow him to do so". In order to establish this, it is necessary to study the temporality of the risk regarding the product at the time it was put into circulation and the development of the knowledge allowing to discover its defect. Since a decision of May 29, 1997, the ECJ has specified that this exonerating cause must be understood in a strict manner. Indeed, since the laboratory's liability is automatic, it cannot be exonerated unless it can prove, with regard to the provisions of article 1245-10 4° of the Civil Code transposing those of article 7e) of the European directive of 1985, that at the time the health product was put into circulation, i.e. the date of marketing of the batch of which the defective product is a part (art. 1245-15 C.civ.), the state of scientific but also technical knowledge did not make it possible to detect the existence of the aforementioned defect.
The said knowledge is not assessed solely according to those in use in the producer's industrial sector; it is imperative to take into consideration "the most advanced level such as it existed at the time the product in question was put into circulation", i.e. it is not necessary to take into account the state of knowledge known or which could be known by the producer, but the objective state according to which the producer is presumed to know it. This means that scientific and technical knowledge, at the time of product release, must be accessible worldwide. To this end, laboratories have a duty of precaution. Judges can then refuse to exonerate the producer for developmental risk in case of risks proven by international studies confirming the dangerousness of similar products, with the same active ingredient causing harmful effects and the withdrawal by some neighboring countries as was the case for Mediator; or in case of negligence (lack of vigilance) on the part of the laboratory which continued the marketing without taking into consideration the reservations of the scientific community as to the harmlessness of the product or the "teratogenic effects on animals" resulting from a study, as was the case for Distilbene.
In addition to the burden of proof, the possible exoneration of producers for developmental risk has important effects on the compensation of victims.

B. Compensation of victims

Laboratories are required to compensate victims when they are liable. Otherwise, the ONIAM can compensate victims of injury caused by a defective health product, after receiving a request for compensation. This claim is made either by mutual agreement procedure or by procedure before a panel of experts.
Under the mutual agreement procedure, concerning vaccines, only victims of a compulsory vaccination can obtain compensation without going to court. Exemptions for injury related to vaccination are allowed in the case of an epidemic for H1N1 or a pandemic for COVID-19, but the victim will still have to prove the causal link. Also, in order to compensate victims who have suffered injury due to Benfluorex (active ingredient of Mediator), an amicable mechanism, governed by the Public Health Code, was set up in 2011 under the control of National Medical Accident Compensation Office (NMACO).
The use of a college of experts, composed of doctors and lawyers, allowing for a global expertise, not interfering with the established jurisprudence -and not medico-centric- in the treatment of serial injuries is appreciated by lawyers who wish that the latter proceeds to the "indemnity quantification of prejudices". However, concentrating this power under the direction of a single body could lead to a dangerous permissiveness in the establishment of a scale.
The large number of victims of a defective health product falls into the category of collective accidents, which is still too hazy in domestic law. Thus, the work of the associations is decisive in order to mobilize victims to obtain collective solutions to an individual injury and to reinforce access to justice through a single procedure for victims of the same or similar injury. In the case of Mediator, numerous proceedings -in summary proceedings, in criminal matters, in administrative matters, before the « CIVI »- were instituted before the above-mentioned mutual agreement procedure was set up, which is superimposed on the existing channels. This system of compensation for victims is financed in a modest way by national solidarity, i.e. the NMACO, and not at all by the producer responsible. Consequently, lawyers in charge of these cases believe that the laboratory responsible for the damage benefits from the system in "two ways: it does not finance the compensation process and benefits from a scale that is much lower than the case law references. "It is suggested that in order to fight against the incoherence of the compensation of victims, the creation of a single reparation fund financed by punitive damages paid by the producers could be a solution.