Legal Sets

110 Pages Posted: 30 Aug 2016 Last revised: 18 Aug 2017

Jeremy N. Sheff

St. John's University School of Law

Date Written: September 22, 2016


In this Article I propose that legal reasoning and analysis are best understood as being primarily concerned, not with rules or propositions, but with sets. The distinction is important to the work of lawyers, judges, and legal scholars, but is not currently well understood. This Article develops a formal model of the role of sets in a common-law system defined by a recursive relationship between cases and rules. In doing so it demonstrates how conceiving of legal doctrines as a universe of discourse comprising (sometimes nested or overlapping) sets of cases can clarify the logical structure of many so-called “hard cases,” and help organize the available options for resolving them according to their form. This set-theoretic model can also help to cut through ambiguities and clarify debates in other areas of legal theory — such as in the distinction between rules and standards, in the study of interpretation, and in the theory of precedent. Finally, it suggests that recurring substantive concerns in legal theory — particularly the problem of discretion — are actually emergent structural properties of a system that is composed of “sets all the way down.”

Suggested Citation

Sheff, Jeremy N., Legal Sets (September 22, 2016). St. John's Legal Studies Research Paper No. 16-0019. Available at SSRN: or

Jeremy N. Sheff (Contact Author)

St. John's University School of Law ( email )

8000 Utopia Parkway
Jamaica, NY 11439
United States
718-990-5504 (Phone)

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