The analysis of judicial decisions is a common practice among legal operators and legal scholars alike. The descriptive character of this practice is rarely called into question. However, those with experience in analysing judicial decisions have at times encountered difficulties in determining the meaning of the propositions that make up such documents. It is not always clear which arguments justify the decision; in other cases, problems concern the operative part of the decision, leaving uncertain what the court has actually decided. Indeed, some legal systems have established forms of clarification proceedings precisely to ask the court to explain what it meant. In any case, problems most commonly arise in identifying the norms that justify the judicial decision. This problem is typically known as that of the interpretation of judgments (in general), or of the identification of the ratio decidendi (in particular). The first expression, however, also encompasses problems arising from attributing meaning to the operative part.

There is extensive literature on the problems surrounding the identification of rationes decidendi, especially from scholars working within common law systems. This is, in fact, a centuries-old debate for which no single satisfactory answer appears to exist. This is because, like all other legal texts, judicial decisions also require interpretation in order to be given meaning. In this sense, judicial decisions suffer from the same problems as the interpretation of any other legal text: ambiguity, vagueness, over-generality, evaluative concepts, and so on.

• The interpretation of judicial decisions is far more problematic than is generally assumed.

Yet alongside these general problems, the identification of rationes decidendi must also contend with a set of specific difficulties. The first is that — whereas constitutions, statutes, and regulations typically provide a canonical formulation to which meaning can be attributed (and from which the relevant norm can be derived) — it is not clear where, within the reasoning section of a decision, the proposition expressing the ratio decidendi is to be found. Indeed, there is even doubt as to whether we should look exclusively within the reasoning section. For example, questions arise as to whether dissenting and concurring opinions may be used to determine the ratio decidendi of a case; similarly, doubts emerge as to whether the operative part of the decision may or should be used to identify the ratio.

The search for a specific linguistic fragment of the judgment is not, however, the only approach to identifying the ratio. Much of the common law literature employs what we might call inductive methods: starting from the reasoning section of the decision and in light of the relevant facts of the case, the norm that was applied is inferred. This method, however, suffers from well-known problems: the norms that could be identified as rationes decidendi are potentially infinite, we do not know which facts are the relevant ones, and so on. The problem is not merely that this method — originally formulated by Goodhart — produces cases of indeterminacy. In addition, we have alternative methods (the Wambaugh test, MacCormick’s test, and others) that can lead, and often do lead, to the identification of different norms as rationes decidendi.

Legal practioners and scholars working in civil law systems typically approach the analysis of judgments with a different, more textual method, which — as noted above — seeks to identify one or more specific propositions as containing the ratio decidendi. To put it briefly, these methods must also confront some of the classical debates in legal interpretation, such as those between subjectivism and objectivism, or between static and dynamic interpretation. This plurality of methods supports the conclusion that the ratio decidendi (or rationes decidendi) of a judicial decision is, in many cases, underdetermined. In such cases, when it is claimed that the ratio decidendi of one or more judicial decisions is a particular norm, a choice is being made among different plausible alternatives. The identification of the ratio thus becomes an act of legal construction.

• The variety of methods for identifying the ratio decidendi leads to legal indeterminacy

One might think that these problems are less pressing where precedents are not binding. However, the difficulties arising from the identification of rationes decidendi are at least partially independent of whether such decisions are binding. Even when they are not, citing a prior decision in which the same conclusion was reached makes the subsequent decision appear better justified. If this is so, then the problem affects virtually all legal systems.

These problems are by no means foreign to legal practice in European countries, nor to the decisions of their courts. In recent years, for example, the interpretation of Court of Justice of the European Union judgments by the Spanish Supreme Court has generated significant friction (C-300/23 – Kutxabank; C-498/22 – Novo Banco and others). Controversies have arisen not only from judicial decisions identifying the ratio decidendi of another judgment, but also from identifications made by press offices — as in the case of the CJEU itself. UEFA and LaLiga “requested” the modification of a CJEU press release in which it was stated that the Superleague project was contrary to EU law, on the grounds that the judgment did not actually say that.

In the same vein, attention should also be paid to publications that systematise the case law of our courts but carry an institutional character. There is a meaningful difference between a legal scholar analysing a judgment in an academic journal and the European Court of Human Rights itself determining, through its Handbooks, what European law amounts to according to that Court or the CJEU. To the best of my knowledge, no rule establishes the legal competence — and its limits — for producing such publications. Moreover, as is inevitably the case, these Handbooks involve a selection of the most significant decisions, typically setting aside others with the same ratio decidendi. The problem is that if we already face difficulties in identifying the ratio of a single decision, those difficulties multiply when it is claimed that several judgments share the same ratio.

• The competence of judicial bodies to authoritatively identify the ratio decidendi has the capacity to reduce the legal indeterminacy.

There are many ways to address the problems of indeterminacy in judicial decisions. Here, however, I am interested in examining the original responses offered by two Latin American legal systems: the Mexican and the Brazilian. Although these have been hastily dismissed by various European scholars as contrary to the supposed essence of precedent, they deserve to be taken seriously as alternatives that can at least partially address this difficulty. I refer to the institution of “tesis” in the Mexican legal system and “súmulas” in the Brazilian system. In brief, these are mechanisms for the institutional identification of rationes decidendi by judges themselves. In other words, it is the judges who — through a later and separate decision from the judgment itself, backed by explicit normative competence — identify the ratio decidendi of a decision. These are not academic products, but exercises of a procedurally regulated competence. Although similar to the work carried out by the Uffizio del Massimario e del Ruolo at the Italian Corte di Cassazione, “tesis” and “súmulas” carry normative force (some “súmulas” are even binding), whereas the Italian “massime” do not.

The Mexican and Brazilian systems, while different from each other, share several significant advantages. The first, and most evident, is that they authoritatively settle which norm constitutes the ratio decidendi of a judicial decision. Second, this response is extremely efficient, as it spares all those affected by a decision the cost of analysing it in full. Third, these instruments are far more widely disseminated than the underlying judgments, primarily because of their brevity: there is a considerable difference between having to read a lengthy judgment to determine the ratio and consulting a document of less than a page. Fourth, once the ratio has been identified, the decisional costs of subsequent cases are reduced, considerably streamlining decision-making. Fifth, at a time when legal databases and, above all, artificial intelligence tools offer near-instant summaries and identifications of rationes decidendi, these institutional mechanisms can drastically reduce potential errors and the resulting legal uncertainty.

These mechanisms, however, also entail a series of risks and problems. The first is that, despite being texts that identify the ratio decidendi, they remain sets of linguistic propositions which, as such, must themselves be interpreted and must therefore confront the very same problems already mentioned — so the difficulty is ultimately displaced rather than resolved. Second, since they are acts separate from the judgment itself, there is a risk that the judges may change their minds and, for instance, identify as the ratio decidendi a norm broader or narrower than the one they applied in the original decision (or indeed a wholly different one). Third, adopting these instruments of institutional identification of the ratio decidendi may bring with it two further problems: that the institutional identification is treated as exhausting and precluding the identification of other rationes. On the one hand, it would be dangerous to foreclose the possibility that another court might challenge the identification already made. On the other, the fact that a ratio decidendi has been institutionally identified at a given moment should not preclude the subsequent identification — not of alternative rationes, but of supplementary ones. Indeed, it is not uncommon for courts to draw upon a past judgment that had attracted little attention in order to extract from it a ratio serving to decide a present case.

• Although they are not perfect, nor are they free from risks and problems, mechanisms such as the Mexican ‘theses’ and the Brazilian ‘súmulas’ would merit a thorough evaluation.

Conferring upon some actor the competence to authoritatively identify the ratio or rationes decidendi of judicial decisions could at least partially resolve the problems stemming from uncertainty about the scope of judicial decisions. We deceive ourselves if we think we harbour no biases regarding solutions to general legal problems that have been formulated from other parts of the world. The mechanisms established in Mexico and Brazil may serve as a starting point for addressing the problems of indeterminacy that judicial decisions generate within our legal systems.

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Álvaro Núñez Vaquero is Professor of Legal Theory at the University of Murcia, Spain. A more extensive analysis in Spanish of this blog post can be found at: https://revistas.uns.edu.ar/disc/issue/view/284. This work forms part of the project “Social Epistemology & Law: functions and resources for legal knowledge” (PID2024-159612NB-I00 DER), funded by the Agencia Española de Investigación of the Ministerio de Ciencia, Innovación y Universidades, whose principal investigators are Juan José Iniesta Delgado and Álvaro Núñez Vaquero.