Legal certainty is frequently associated with the idea that legal subjects must be able to anticipate how their actions will be classified by the legal system. Yet, as soon as the notion of predictability is analysed with rigour, the apparently simple intuition proves far more demanding than it initially appears. Predictability can only operate as a criterion of legal certainty if a series of conceptual, epistemic and methodological commitments are explicitly adopted. Without these commitments, appeals to predictability remain superficial and inert.
In Part I, we touched upon two commitments of predictability, related to agents and contexts, as well as methodology. Here, in Part II, we will explore the commitment related to mandates or outcomes – that is, to decide on the object of the prediction itself.
Commitment to Mandates or Outcomes
A widely shared starting point in the literature is that legal certainty at least involves the ability to anticipate the legal consequences that will be attached to a future action or omission. This presupposes, first, that addressees are in a position to predict which facts will be treated as normatively relevant by legal decision-makers and which normative consequence will be correlated with those facts, and second, that legal systems are designed so as to maximise, as far as possible, this capacity to predict. Understood in this way, predictability is not merely an epistemic virtue; it is part of the architecture that enables agents to plan their lives.
In this perspective, law is conceived as an instrument that allocates prohibitions, obligations and protected spheres of liberty, thereby delineating a menu of means that individuals may use to pursue their life plans. Legal certainty protects personal autonomy by allowing agents to know in advance which behaviours are excluded, which are required, and within which margins they can act without undue interference. Appeals to predictability, however, are not neutral: they presuppose programmes of study and of institutional reform. On the descriptive side, they commit us to devising indicators that tell us whether a given practice of application is predictable. On the normative side, they commit us to proposals aimed at preserving or increasing predictability, or at least at avoiding institutional changes that would undermine it. In both cases, the relevant perspective is ex ante: the question is whether, from the present, it is reasonable to form true beliefs about what the system will do in the future.
These programmes cannot even begin without a prior decision about what, exactly, is being predicted. At a minimum, one must decide whether the object of prediction is the behaviour of agents according to valid norms, the behaviour of agents (that follows or not valid norms), or some combination of both. This leads to a distinction between the predictability of legal mandates and the predictability of outcomes, and to a further refinement concerning the status of justified non-application.
Predictability of Legal Mandates
On one reading, predictability is attached to legally authorised reactions. The acts that matter for legal certainty are the acts that qualify as valid applications of legal norms. Predictions, in this sense, concern only the content of legal norms—both their antecedent and their consequent—and the use of those norms in accordance with that content. What is to be anticipated is how the legal system, properly applied, would classify a certain type of conduct and which consequences it ought to attach.
From this point of view, predictability is conceptually connected to a specific notion of efficacy. Efficacy is not defined as mere regularity of behaviour, but as guidance: norms are efficacious when their addressees know of their existence and, precisely because of that explicit regulation, choose to conform their conduct to the state of affairs prescribed. For predictability to attach to mandates, norms must be identifiable, their content must be determinable, and adjudicators must actually use them as reasons in their decisions. A norm that remains formally valid but is not used in institutional practice no longer contributes to legal certainty; it cannot structure expectations and ceases to guide conduct.
In this framework, a legal system is descriptively secure when valid norms can be identified, their content is sufficiently stable, and their use by courts and administrative bodies generates regularities that agents can factor into their planning. Conversely, a system is insecure either when it is impossible to determine which norms form part of the system or what they mean, or when their use is so ineffective that it does not condition social interactions in any significant way. Crucially, the predictability of invalid legal acts—such as systematically unlawful decisions or practices—does not count as legal certainty, because the concept is defined in terms of the authorised use of valid norms.
Predictability of Outcomes
A second reading, equally coherent but based on a different commitment, treats predictability as a property of social outcomes rather than of authorised mandates. Here, what is to be predicted is how public and private agents will in fact react to a given course of action, regardless of whether that reaction conforms to valid norms. Predictability is thus a strictly sociological property: a system is predictable when patterns of behaviour, whether lawful or unlawful, are sufficiently stable to support reliable expectations.
Consider a simple example. Imagine a city in which rules on pedestrian crossings and stop signs are systematically ignored by drivers, and the police make no effort to enforce them. The micro-system of traffic rules is, from the standpoint of norm-guidance, in a state of anomia: valid rules exist, but they are not used as reasons for action. From the point of view of the predictability of legal mandates, this scenario would be classified as deeply insecure: the law does not effectively guide conduct. From the point of view of outcomes, however, the system is highly predictable. Every time one approaches a pedestrian crossing or a stop sign, one can safely expect that vehicles will behave as if the signals did not exist. This regularity allows individuals to plan how to move around the city and to minimise their risk of accidents, not because the law is effective, but because the pattern of illegality is stable.
The same contrast appears in other contexts. It may be perfectly predictable that certain serious violations of rights will remain in impunity, or that certain corrupt practices—bribery, trafficking of influence, political pressure—will determine the allocation of public resources. This outcome-oriented use of predictability is familiar in descriptions of authoritarian regimes and authoritarian exercises of power, where citizens can reliably anticipate that institutions will react in a systematically abusive, selective or repressive manner, even if such reactions are manifestly at odds with the official legal framework. From the standpoint of mandates, these regularities are paradigmatic instances of insecurity: they signal the failure of norm-guidance. From the standpoint of outcomes, they may qualify as a form of “secure injustice”: the injustice is stable enough to be anticipated. The core disagreement between the two readings lies in whether the efficacy of valid norms is treated as a conceptual component of legal certainty. For a mandate-based conception, a system in which stable illegality, corruption or authoritarian arbitrariness determine behaviour is, by definition, insecure. For an outcome-based conception, such a system may still count as secure, provided it remains sufficiently regular to sustain planning.
Cases of Justified Non-application of norms
The distinction between mandates and outcomes becomes more complex in cases of non-applicability of norms is legally justified or even required. These are scenarios in which the system itself generates a higher-order mandate not to use certain norms or precedents, so that the “absence” of application is not a deviation from legality but an expression of it.
One important example is provided by what have been called negative precedents. Some decisions, because of their content or their effects, are gradually reclassified by the legal community as exemplars of how cases ought not to be resolved. They retain doctrinal and pedagogical relevance, but as warnings rather than as models. The United States Supreme Court’s decision in Dred Scott v. Sandford (1857) is a paradigmatic case: over time, it came to be treated as a canonical illustration of the structural misuse of judicial authority. In such contexts, the correct legal effect of the precedent is its non-use: courts are expected not to reproduce the line of reasoning it embodies.
From a mandate-based perspective, these cases are not instances of insecurity but of a refined form of security. There is a mandate not to rely on certain norms or precedents, and the system is predictable when that mandate is observed. Predicting the non-application of a negative precedent is, in this sense, predicting an authorised legal consequence. This forces the predictabilist to distinguish between illicit non-application, which undermines norm-guidance, and juridically authorised non-application, which expresses norm-guidance through abandonment. Without this distinction, many scenarios of justified anomia—such as the refusal to apply unconstitutional norms, the systematic abandonment of doctrinal positions that are considered incompatible with higher-level principles, or the exclusion of structurally vicious precedents—would be misclassified as instances of insecurity.
Is All the Same?
Once the object of prediction is clarified, a predictabilist conception of legal certainty commits itself to a series of further decisions. It must specify which agents offer predictions that are normatively relevant for assessing whether a practice is predictable: any person can make a forecast about how courts will decide, but only some predictors—judges, practising lawyers, scholars, perhaps even informed non-lawyers—will be treated as epistemically authoritative by a given legal community. It must decide which social behaviours are relevant: whether the focus is on specific decisions in individual cases or on the emergence of recurring practices and patterns of adjudication. And it must choose which methodologies are acceptable for generating predictions: from doctrinal reconstruction and interpretive reasoning to statistical models, empirical studies of judicial behaviour, or mixed approaches.
These decisions are not merely technical. They determine the kind of studies that will be considered meaningful and the kinds of institutional reforms that can be justified. For example, if one adopts a mandate-based conception of certainty, it will be natural to design indicators that measure the stability of interpretive doctrines, the coherence of lines of case law and the degree to which valid norms are actually used in reasoning. If one adopts an outcome-based conception, indicators will instead track behavioural regularities, regardless of their legality. In both cases, the underlying assumption is that predictions are formed ex ante, using presently available information about the content of the system, its practices, and its likely reactions to new cases.
The threefold distinction—mandates, outcomes, authorised non-application—reveals that predictability cannot be invoked without committing to a substantive structure of legal consequences. A predictabilist must therefore determine:
- whether predictability attaches to validity, behaviour, or both.
- whether certainty can arise from patterns of illegality.
- whether predicting non-application contributes to legal certainty.
- how to classify stable dysfunctions within the evaluative architecture.
These commitments are foundational; failing to adopt them collapses the notion of predictability into conceptual ambiguity.
Coming up next
We have already explored three commitments of predictability: in Part I, two commitments related to agents and contexts, and to methodology; in Part II, a commitment related to mandates or outcomes.
In the last part of this series of blog posts, Part III, we will see a final commitment: the related to predictions as epistemic tools.
To read more about this and engage in the discussion, check out this recent paper: García Yzaguirre, V. (2024). Seguridad jurídica y predictibilidad: Una propuesta de reconstrucción. Archiv für Rechts- und Sozialphilosophie [LINK]. You can also check out the author’s previous published work on the same topics. [LINK]
SUGGESTED CITATION: García-Yzaguirre, Víctor: “Legal Certainty and the Commitments of Predictability (Part II)”, FOLBlog, 2025/12/15, https://fol.ius.bg.ac.rs/2025/12/15/legal-certainty-and-the-commitments-of-predictability-part-ii/