Do highest courts advance legal unity?

Do highest courts advance legal unity?

From a theoretical perspective, highest national courts cannot advance the legal unity of their legal systems through case-by-case adjudication. Only less encompassing forms of legal unity are theoretically feasible.

Most national legal systems entrust their highest national court with the task of advancing internal legal unity. In the Netherlands, this task has been allocated to the Supreme Court of the Netherlands (SCN) in relation to civil, penal and tax cases. It is presumed the SCN fulfills this task through case adjudication and a system of informal precedent. My research aims to determine whether there is empirical evidence to support this contention and to clarify the mechanism behind it. This requires a theoretical framework that offers a clear understanding of legal unity and its advancement through highest court adjudication. In this blog, I outline two points for discussion on the basis of a survey of relevant academic literature on the concept of coherence, that underline the need for and importance of a more sophisticated and differentiated approach to the notion of legal unity.

(i) Highest courts cannot advance ‘global’ coherence through adjudication.

The notion that highest courts are able to advance legal unity, which is most often understood as global coherence, i.e. legal unity within the national borders of their jurisdiction, is theoretically problematic. The arguments of excessive voluntarism (Raz, 1992) and psychological implausibility (Levenbook, 1984) are intuitively persuasive. These arguments convey the objection that it is humanly improbable if not impossible to consciously test each of our propositions on their coherence, let alone to assess the coherence between those (internal) propositions and the complete set of (external) propositions within a given legal order.

(ii) Highest courts can advance less encompassing forms of coherence.

Facing these difficulties, it has been suggested that highest courts should focus on making their decisions internally coherent (‘local adjudicative coherence’). Soriano (2003) calls this a modest notion of coherence in legal reasoning in the context of the European Court of Justice. The reasoning underlying each decision, on itself and in its ‘local’ context, can be perfected to comply to several of the epistemological traits of a coherent theory (Kress, 2010). Stepping outside the four corners of the ruling, taking into consideration other propositions in the same branch of law (‘area-specific’ coherence) or in other branches or jurisdictions (which I tentatively call ‘transversal’ coherence), generates additional problems, such as the problem of selection. As Raz (1992) pointed out, coherence may help us to select those precedents that cohere with the propositions we already view as correct, but it will not indicate whether those precedents or our presuppositions are justified. Here, Amaya’s model of optimal coherence (2011) may offer relief. She proposes encountering problems of under- and over-consideration through a process of epistemically responsible inference to the best legal explanation and contextual generation and evaluation of alternative hypotheses. This model does not expect judges to compute each and every internal (i.e. mental) and external proposition (i.e. within a legal order), but accepts a discrete, psychologically plausible set of hypotheses. Empirical research by Sunstein, Kahneman, Schkade & Ritov (2002) seems to suggest judges are indeed capable of moving towards coherence that transcends the context of a decision or a specific branch of law.


Levenbook, B. (1984). Coherence in Legal Reasoning. Law and Philosophy 3, 355-374.

Raz, J. (1992). The Relevance of Coherence. Boston University Law Review 72, 273-321.

Soriano, L.M. (2003). A Modest Notion of Coherence in Legal Reasoning. A Model for the European Court of Justice. Ratio Juris 16, 296-323.

Kress, K. (2010). Coherence. In Patterson, D. (ed.). A Companion to Philosophy of Law and Legal Theory. Oxford: Wiley-Blackwell.

Amaya, A. (2011). Legal Justification by Optimal Coherence. Ratio Juris 24, 204-329.

Sunstein, C., Kahneman, D., Schkade, D., & Ritov, I. (2002). Predictably incoherent judgments. Stanford Law Review, 54, 1153-1215.


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