Analogy (law)¶

A legal reasoning method extending a rule or precedent to an unresolved case because legally relevant similarities outweigh material differences.

Version: v2 · 2026-09-19 · History
Domain-specific #: 3278
Domain group: Professional & Organizational Practice
Origin domain: Law & Governance
Subdomain: Legal Reasoning → Law & Governance

Core Idea¶

Civil-law statutory analogy and common-law analogical precedent draw authority differently, and criminal legality can prohibit analogy against an accused; surface similarity never suffices without the rule’s rationale. The decision maker identifies the source case or provision, extracts its legally relevant reason, maps that reason to the new facts, tests disanalogies and extends or withholds the rule. The abstraction is therefore identified by a declared carrier, a transformation or constraint over that carrier, and an invariant that tells an analyst whether the named structure is genuinely present.

How would you explain it like I'm…

Does the Old Reason Fit?

When a judge gets a new kind of problem, they can look at an old case that was a lot like it. They ask why the old case was decided that way. If that same reason fits the new problem, they decide it the same way, but if something important is different, they do not.

Using Old Rules for New Cases

Analogy in law is when a judge uses a rule from an earlier case or law to decide a new case that is not directly covered. The judge figures out the reason behind the old rule, checks whether that reason fits the new facts, and looks for important differences. If the reason fits and there are no big differences, the rule can be extended; if not, it is not. Different legal systems use analogy differently, and in criminal cases many systems do not allow analogy to be used against the accused person.

Extending Rules by Their Reason

Legal analogy is reasoning that extends, or refuses to extend, an existing rule to a new case by comparing it with a source case or provision. The decision maker identifies the source, works out its legally relevant reason (its ratio or purpose), maps that reason onto the new facts, tests for material differences, and then extends or withholds the rule. Surface similarity is never enough without the rule's rationale. Legal traditions draw authority for analogy differently: civil-law systems often reason by analogy from statutes, while common-law systems reason from precedents. In criminal law, the principle of legality can forbid analogy against an accused person, so whether analogy is permitted at all depends on the field and jurisdiction.

Analogy in law is reasoning that extends or withholds a legal rule for an unresolved issue by comparison with an authoritative source. The decision maker identifies the source case or provision, extracts its legally relevant reason (ratio or purpose), maps that reason onto the new facts, tests disanalogies, and either extends the rule or declines to. Similarity of facts matters only insofar as it tracks the rule's rationale. Authority is drawn differently across traditions: civil-law statutory analogy extends provisions to gaps, while common-law analogical reasoning works from precedent. In criminal law, the principle of legality can prohibit analogy against the accused. A well-formed analysis states the jurisdiction and tradition, the unresolved issue, the authoritative source, its facts and holding or provision, its ratio or purpose, the mapped similarities, the material differences, whether analogy is permitted, and the resulting rule and remedy.

Scope of Application¶

Analogy (law) belongs to legal reasoning and is useful where the analyst can specify the typed legal reasoning carrier, defining objects and relations, parameters, conventions, evidence, boundary cases, and comparison targets, then evaluate the jurisdiction and legal tradition, unresolved issue, authoritative source, source facts and holding or provision, ratio or purpose, mapped similarities, material differences, permission or prohibition on analogy and resulting rule and remedy are explicit. The scope is broad within that domain but bounded by the need for the jurisdiction and legal tradition, unresolved issue, authoritative source, source facts and holding or provision, ratio or purpose, mapped similarities, material differences, permission or prohibition on analogy and resulting rule and remedy are explicit.

Clarity¶

The abstraction clarifies a crowded vocabulary by making the jurisdiction and legal tradition, unresolved issue, authoritative source, source facts and holding or provision, ratio or purpose, mapped similarities, material differences, permission or prohibition on analogy and resulting rule and remedy are explicit the center of the account. A claim should name the carrier, the governing operation or relation, the applicable assumptions, and the recognition test.

Manages Complexity¶

Without the abstraction, an analyst must reason directly over many local details: the carrier roles, admissibility assumptions, competing conventions, derived invariants, boundary cases, and proof or validation obligations specific to Analogy (law). Analogy (law) compresses them into the roles in the structural signature. That compression permits comparison across instances without erasing the variables that determine validity. It also exposes which details may be varied safely and which are constitutive.

Abstract Reasoning¶

Identify the carrier. State what the elements, states, objects, or observations are: the typed legal reasoning carrier, defining objects and relations, parameters, conventions, evidence, boundary cases, and comparison targets. Reject examples whose alleged carrier belongs to a different problem.
Lock the constitutive rule. Express the jurisdiction and legal tradition, unresolved issue, authoritative source, source facts and holding or provision, ratio or purpose, mapped similarities, material differences, permission or prohibition on analogy and resulting rule and remedy are explicit independently of one notation or implementation.

Knowledge Transfer¶

Knowledge transfers strongly among subfields of legal reasoning because they reuse the typed legal reasoning carrier, defining objects and relations, parameters, conventions, evidence, boundary cases, and comparison targets, The decision maker identifies the source case or provision, extracts its legally relevant reason, maps that reason to the new facts, tests disanalogies and extends or withholds the rule., and type the carrier, state every parameter and convention in the definition, test that the jurisdiction and legal tradition, unresolved issue, authoritative source, source facts and holding or provision, ratio or purpose, mapped similarities, material differences, permission or prohibition on analogy and resulting rule and remedy are explicit, compare the nearest accepted identity, and report counterexamples, uncertainty, and limiting cases.

Relationships to Other Abstractions¶

Current abstraction Analogy (law) Domain-specific

Parents (1) — outgoing typed relations

Analogy (law) is a kind of Analogy Prime

It remains its own entry because its identity is fixed by the jurisdiction and legal tradition, unresolved issue, authoritative source, source facts and holding or provision, ratio or purpose, mapped similarities, material differences, permission or prohibition on analogy and resulting rule and remedy.

Hierarchy paths (2) — routes to 2 parentless roots

Analogy (law) → is a kind of Analogy → is a kind of Comparison

Show alternative path (1)

Neighborhood in Abstraction Space¶

Analogy (law) sits in a crowded region of the domain-specific corpus (2^nd percentile for distinctiveness): several abstractions share nearly its structure, so a description that fits it tends to fit its neighbors too.

Family — Contract, Property & Legal Doctrine (44 abstractions)

Nearest neighbors

Computed from structural-signature embeddings · 2026-10-25