The causal relationship is one of the pillars of liability, whether liability on the basis of fault or the existing liability without the fault of management, and the injured party must prove this link in all administrative liability systems. In view of the difficulty of proving the causal link between the act of damage and the act attributed to the administration related to the practice of modern scientific and technical administrative activities, the weakness of the injured party’s position regarding the administrative lawsuit, and the desire of the administrative judiciary to alleviate its burden, the administrative judiciary in France tended to resort to evidence, whether legal or judicial, This is to prove the causal link between the administration’s act and the damage, which leads to the temporarily liberating the injured from the burden of proof originally entrusted to him in this regard and transferring it to the defendant administration, so that the injured party is not obligated to prove the causal link, and it is sufficient to prove only the act attributed to the administration and the damage. The causal relationship is limited only to providing evidence and indicators that lead to the assumption that the damage is attributed to the act attributed to the administration. Therefore, the administrative judiciary resorted to the assumption of a causal link between the act attributed to the administration and the damage, in order to face the certain uncertainty in the establishment of a causal relationship. Administration, despite the lack of scientific confirmation of the percentage of that damage to that act. There are many judicial applications through which the administrative judge applies the presumption of causation, and perhaps the most prominent areas in which this mechanism has been resorted to is compensation for damages related to the medical field, as well as compensation for damages from nuclear tests. The presumption of causation has developed in the perspective of administrative judiciary. Traditionally, assumptions of causality are studied in relation to the cause of damage. The damage is present and confirmed, but its cause is not known with certainty, and it will be assumed. Presumption is then a way of causal explanation of harm. But the administrative judge can also assume a result. This will be the case when it is no longer a matter of assuming the cause of the damage but of assuming the consequences of a particular fact. From the point of view of causation, the administrative judge can thus overcome causal uncertainty in terms of the cause of the damage and the consequence of the cause. This is why the distinction is made between the assumption of cause and the assumption of effect.