Medical Liability and Causation: Cassation Order No. 17006 of 24/06/2025 and the Distinction Between Material and Legal Causation

Medical liability is a highly complex issue, often encountering difficulties in establishing a certain causal link between the healthcare professional's conduct and the harm suffered by the patient. This complexity increases exponentially when the patient has pre-existing conditions that may have contributed to, or even caused, the damage. In this intricate scenario, the Order of the Court of Cassation No. 17006 of June 24, 2025, provides a fundamental clarification, outlining the boundaries between material and legal causation.

The ruling, which saw parties B. D. and A. in opposition and overturned a previous decision by the Court of Appeal of Naples, aligns with established jurisprudence but requires continuous refinement, especially in such a sensitive area as healthcare.

The Heart of the Matter: Material Causation vs. Legal Causation

The focal point of the judgment concerns the correct identification of the causal link in the presence of concurrent causes, i.e., factors that, along with the doctor's conduct, contributed to the occurrence of the injurious event. The Cassation Court, in fact, reiterates the importance of distinguishing between two fundamental conceptual levels:

• Material (or factual) causation: This concerns the relationship between the healthcare professional's conduct and the damaging event. It asks whether the doctor's negligent, imprudent, or unskillful conduct was a necessary condition for the occurrence of the damaging event.
• Legal causation: This refers to the relationship between the damaging event and the specific compensable damages. Here, the extent of compensable damage is assessed, taking into account any pre-existing or supervening factors not attributable to the healthcare professional.

This distinction is crucial for correctly assigning liability and determining the amount of compensation.

The Cassation's Ruling: Analysis and Implications

In matters of civil liability, where the occurrence of a damaging event may appear attributable, from an etiological perspective, to the concurrence of the healthcare professional's conduct and the natural factor represented by the patient's pre-existing pathological condition (which is not linked to the aforementioned conduct by a causal dependency), the judge must ascertain, on the level of material causation (correctly understood as the relationship between the conduct and the damaging event, pursuant to Article 1227, paragraph 1, of the Italian Civil Code), the etiological efficiency of the conduct with respect to the event, applying the rule of Article 41 of the Italian Penal Code (according to which the concurrence of pre-existing, simultaneous, or supervening causes, even if independent of the perpetrator's action, does not exclude the causal relationship between the action or omission and the event), so as to attribute the damaging event entirely to the perpetrator of the illicit conduct, and then proceed – possibly even with equitable criteria – to assess the different efficiency of the various concurrent causes on the level of legal causation (correctly understood as the relationship between the damaging event and the individual compensable damages that resulted) in order to assign to the perpetrator of the conduct, liable in full on the level of material causation, a compensation obligation that does not include those damages not etiological attributable to the damaging event, but rather determined by chance, which must be considered the patient's pre-existing pathological condition that, in turn, is not etiological attributable to the healthcare professional's negligence, imprudence, and lack of skill.

This ruling is of extraordinary importance. The Court clarifies that, regarding material causation, the judge must apply Article 41 of the Italian Penal Code. This means that the concurrence of pre-existing causes (such as a patient's pathology), simultaneous, or supervening causes does not exclude the causal relationship between the healthcare professional's action and the damaging event, unless the concurrent cause was the sole determinant of the event. If the doctor's conduct was etiological efficient, the damaging event is entirely attributed to the healthcare professional. This approach ensures that liability is not evaded simply due to the presence of pre-existing factors.

However, it is on the level of legal causation that the modulation of compensation comes into play. Here, the judge, even with equitable criteria, can assess the efficiency of the various concurrent causes. If the patient's pre-existing pathology is not causally linked to the doctor's conduct (i.e., the doctor did not worsen or cause that pathology) and independently contributed to the final damage, then the damages attributable to it may be considered as determined by "chance." In this case, the healthcare professional's compensation obligation will not include such damages but will be limited to those directly attributable to their conduct.

Practical Application and Legal References

The Cassation Order offers clear guidance for judges called upon to evaluate cases of medical liability. It emphasizes the need for a rigorous and two-phase analysis:

• Phase 1 (Material Causation): It is ascertained whether the healthcare professional's conduct contributed, according to the principle of