top of page



A confrontation between rival supporters of two São Paulo football clubs recently resulted in the deaths of two young fans who were killed by shots fired during the disturbance. It is sad to report this type of occurrence is far from occasional or exceptional and it suffices to watch any sports match on a Sunday to witness the unfortunate practice of fighting between supporters of rival teams. These melees often result in significant losses and injuries that must be indemnified. But indemnified by whom? How does one substantiate causation of the harm suffered and impute liability to the individual alleged to be responsible?

The analysis presented here deals with situations where the harm is caused by an unidentifiable member of a known group. While it is possible to identify the social segment that generated the harmful conduct, it is impossible to individualize such conduct, “hidden” as it is amidst the mass of individuals who form the group. This raises questions of whether group liability can exist absent the proper identification of the agent who caused the damages, and how to attribute causation and damages to his behavior.

Before delving into an analysis of the circumstances surrounding this case and the elements needed to understand it, we must first address the theme of co-authorship as used to develop the theory of collective liability.

i. Co-authorship and the distribution of liability: complementary causation (concomitant causes) and cumulative causation (concurrent causes).

Investigating causation can lead to the realization that damages are actually the result of various conduct or activities that together led to that particular loss occurring. This arises either because each person’s conduct, in itself, is sufficient to cause the outcome (concurrent causation), or because each of the forms of conduct requires some other action or conduct to complement it in order to generate the harm in the manner it occured (complementary or concurrent causation).

Identifying a plurality of individuals potentially liable for the harm demonstrates the phenomenon of co-authorship or co-participation, which allows us to see the individualization of the conduct of all the actors who together contribute to producing the harm. Co-authorship will be delimited when we are confronted with situations of multiple causation, thus giving rise to the liability of all those whose conduct contributed to the harm.

Both complementary causation and cumulative causation, whether simultaneous or successive, present questions concerning the degree of liability of each of the tortfeasors. Should they all answer for the result as it occurred, or should there be an equitable apportioning of liability to the extent of each actor’s participation in causing the harm? In other words, will there be joint liability among all the tortfeasors, regardless of their degree of fault, or will each of them only be liable to the extent of their participation in resulting the harm?[iii]

The general rule provides for joint liability where simultaneous causation occurs (article 942, Civil Code[iv]). As Ignacio de Cuevillas Matozzi sees it, the application of this rule must always be considered in accordance with the principles of equity. Only then can indemnificatino be permitted where there are multiple causes. Requiring individualized proof of the causal link of each actor in performing the harmful act would compromise the very purpose of civil liability, which is to repair unjust harm. The demonstration of this proof would be render the system unworkable, especially on account of the principle of unity of damage.[v]

Conceptualizing harm as the result of a single item – seeing as the offense is single – suggests the use of joint fault. In the classic example of simultaneous complementary causes, if two people, unaware of each other’s actions, administer poison to a third party who dies as a result, both will held jointly liable for the death (thereby identified as a single outcome), regardless of whether they knew that each of their actions alone was insufficient to cause death. That is, even if one of the agents later proves that the poison they administered was not strong enough to cause a person’s death on its own, they would still be held liable, at civil law, on account of their causal contribution to the death.[vi] Likewise, if the two doses of poison were each independently capable of causing death, we would then have a situation of concurrent causation leading to the same result as individual liability but also allowing one of the parties to allege the irrelevance of their conduct, given that death would result anyway due to the conduct of the second party who administered an equivalent dose.[vii]

Investigating multiple causation becomes relevant to the study of collective liability where there are several actions that possibly caused the harm (theoretically, concurrent causation), and where it is impossible to identify the particular conduct specifically, and solely, responsible. This raises the question of whether an obligation exists on the part of the group to indemnify and whether the nature of this liability is based in a theory of co-authorship or cumulative causation, among others, as we shall see below.

ii. Alternative causation: theory and application

Typically identified with co-authorship – even though it conceptually does not refer to the same exact elements, as we shall see – “anonymous fault”[viii] as coined by Ignacio de Cuevillas Matozzi, or “alternative causation” or “collective liability”[ix] as referred to by Portuguese authors, is characterized by harm caused by an unidentifiable member of a determinable and known group.[x] In other words, any of the group’s members could have caused the harm, hence the label “alternative causation”.

A brief critique concerning the nomenclature used to explain this theory is in order. Adopting the phrase “anonymous fault”, which symbolically expresses the issue in question is, nonetheless, by its very nature, misleading. The concepts raised in this theory can refer to situations of both subjective and objective civil liability, which explains why it is wrong to speak of fault. Furthermore, the notion of fault are for this purpose factors that attribute responsibility rather than identifying the responsible party, inasmuch as they qualify the conduct or activity by establishing whether it creates an obligation to indemnify. It would be more appropriate to deal with this situation using the expression “anonymous conduct”, without classifying it as blameworthy or culpable, or even “anonymous cause”, since in reality causation – an element to identify the responsibility party – is anonymous.

Likewise, the idea of “collective liability” is exaggerated and overly broad in that not all members of the group are personally responsible for the damage that was brought about. Proving that their participation in the damaging event was impossible suffices to negate their liability.[xi] Moreover, the expression “collective” suggests the idea of joint conduct or a joint activity, whereas the truth is that this situation refers to individual conduct (or to multiple individuals’ conduct) that is not identifiable and confused with the purpose of grouping several actions together, even though it is the outcome of this.

The best expression to define this situation is, without a doubt, “alternative causation”. But even this expression can be the object of critique. Suffice it to think of the meaning of “alternative”, which conveys the idea of possible choices. Alternative causation, however, does not symbolize the substitution of responsibility, that is, it does not entail identifying individual and alternative causes. Instead, there exists one single causal connection that defies direct identification. This explains the theory’s presumption with respect to the group as a whole. However, it is not a matter of claiming that one individual or another is responsible, but only the group itself, since it is not possible to point to the individual whose conduct was the direct cause of the damage. This expression, “alternative causation”, being closest to the real function of the theory in question, will be preferred throughout this text.

In regards to the proclaimed similarity between co-authorship (multiple causation) and alternative causation, one point has to be cleared up to avoid theoretical distortions. The necessary reservation has to do with attributing liability. There are three possible consequences of identifying the existence of multiple causation, as seen above: 1) liability is jointly apportioned among those alleged responsible for the damage (article 942, CC); 2) liability is apportioned based on each agent’s causal contribution to the injury; and 3) liability is attributed to only one of the agents, if it is possible to identify a separation between the causal connection of the two successive acts. Theoretically, the liability derived from alternative causation does not fit any of the hypotheses of attribution of liability described above. This is because the harmful conduct can be unified, which does not characterize multiple causation. Furthermore, multiple causation refers to the capacity for causal contribution of several conducts or actions to the damaging events, which does not occur in the case of alternative causation, where th