Theory & Model of the Legal Rule (jle-theory-model)

When to trigger

• A referee asks "what is the economic mechanism / what model rationalizes this legal effect?"
• A reduced-form effect of a rule is credible but its economic meaning (deterrence vs. incapacitation, price vs. quality) is ambiguous
• You want a welfare statement about a legal rule, an optimal-penalty result, or a comparative static the raw estimate cannot deliver
• The paper is theoretical and you need its predictions about a legal rule to be recognizable and testable, not decorative

The JLE theory tradition

JLE's theory is price theory applied to legal rules — Becker on crime (expected punishment = probability × severity), Coase on bargaining and entitlements, Calabresi/Posner on liability and least-cost avoidance, Stigler/Peltzman on regulation and capture, the litigation-selection logic of Priest–Klein. Theory earns its place when it names the mechanism, maps a coefficient to a structural object, delivers a welfare or optimal-rule result, or generates a comparative static you then test. JLE accepts genuinely theoretical papers, but even pure theory should speak about a legal institution a reader can recognize. Pick the lightest tool that does the job; do not let a model silently replace the identification an empirical design provided.

Modeling craft

1. Make the legal rule a primitive. The penalty schedule, the liability standard, the entitlement, the enforcement probability should be objects in the model, not afterthoughts — that is what makes it law-and-economics rather than generic theory.
2. Comparative statics before estimates. Derive the sign predictions about the rule first; test them after. Predictions invented post hoc read as HARKing the theory.
3. Sufficient statistics where possible. Express the welfare/optimal-rule object as a function of estimable elasticities (deterrence elasticity, demand response to a penalty) rather than estimating a full structural model — credibility stays in the design.
4. Tie any structural parameter to the institution. If you do estimate a model, each parameter should map to a data feature and a legal mechanism, validated against an untargeted moment.
5. State scope and what the model omits — general-equilibrium feedbacks, enforcement endogeneity, behavioral departures from rational deterrence.

Canonical JLE modeling templates (reach for the closest)

Rather than build from scratch, most JLE theory contributions extend one of a few canonical frames. Name the one you are using; referees recognize them and will judge your extension against them.

• Deterrence (Becker): expected punishment = probability of apprehension × severity; offenders respond to the margin. Use for crime, enforcement, regulatory penalties, tax evasion. The comparative static you usually want: how an outcome moves with the expected (not nominal) penalty.
• Liability / least-cost avoider (Calabresi–Posner): negligence vs. strict liability allocate care between injurer and victim; the efficient rule minimizes the sum of accident and avoidance costs. Use for torts, products liability, accidents.
• Bargaining & entitlements (Coase): with low transaction costs the efficient outcome is invariant to the entitlement; with frictions the rule matters. Use for property, nuisance, contract remedies.
• Regulation & capture (Stigler–Peltzman): regulation is supplied to politically organized groups; the regulator trades off producer and consumer support. Use for entry licensing, rate regulation, occupational rules.
• Litigation selection (Priest–Klein): which disputes settle vs. go to trial is endogenous, so trial samples are selected. Use whenever you study court outcomes — it warns against reading trial win-rates naively.

Checklist

• Theory's job named (mechanism / mapping / welfare-or-optimal-rule / comparative statics / standalone)
• The legal rule (penalty, standard, entitlement, enforcement) is a primitive in the model
• Lightest adequate tool chosen; for empirical papers, the model does not upstage the design
• If a sufficient statistic: the estimable elasticities and validity assumptions stated
• If structural: each parameter tied to a data feature and a legal mechanism; untargeted-moment validation
• Comparative statics / sign predictions derived before they are tested
• Welfare/optimal-rule numbers carry uncertainty and a stated scope (what is omitted)

Anti-patterns

• A "model" that adds notation but no testable prediction about the legal rule
• Comparative statics produced after seeing the results (HARKing the theory)
• Letting model assumptions quietly substitute for the identification the empirical design should provide
• A welfare or optimal-penalty number with no uncertainty and no statement of omissions
• Generic mechanism-design theory with no recognizable legal institution (drifts toward a theory journal)

Worked vignette (illustrative)

A clean RD shows a sentence-enhancement threshold cuts re-offending by 5pp (s.e. 1.4). The number is credible but the policy question is whether harsher sentences deter or merely incapacitate. Instead of a full dynamic crime model, the paper uses a Becker-style framework: the deterrence channel predicts a drop in new offenses by those still at liberty near the margin, while incapacitation predicts a drop only during custody. A sufficient-statistic argument expresses the marginal deterrence value as the offense elasticity to expected punishment (estimated from the RD) times the social cost per offense (calibrated). The framework yields a testable split the paper then confirms in the timing of effects — the JLE ideal of theory that names and tests a legal mechanism.

How much theory is too much for an empirical JLE paper

JLE publishes both empirical and theoretical work, so the dial is wider than at an empirical-only journal — but for an empirical submission the model should still stay in its lane:

• Too little: a reduced-form effect with no framework, leaving the referee to ask "deterrence or incapacitation? price or quality?" with no way to tell.
• Right: a compact framework that issues a sign or comparative-static prediction the data then adjudicate, plus (if needed) a sufficient-statistic mapping to a welfare or optimal-rule number.
• Too much: a fully solved structural model whose assumptions, not the legal variation, now carry the identification — at which point reviewers ask why the empirical design was needed at all.

For a theoretical submission the calculus inverts: the model is the contribution, but it must still concern a recognizable legal institution and yield results an empiricist could in principle confront with data.

Referee pushback mapped to the theory fix

• "What is the mechanism behind this legal effect?" → Add a short framework (deterrence / liability / bargaining) with a sign prediction you then test — not more notation.
• "This number is not policy-relevant without a welfare statement." → Express the optimal-rule object as a sufficient statistic of estimable elasticities; state the validity assumptions.
• "Your model just assumes the result." → Make the legal rule a primitive, tie each parameter to a data feature and a mechanism, and validate against an untargeted moment.

Output format

【Theory's job】mechanism / coefficient-to-structural mapping / welfare-or-optimal-rule / comparative statics / standalone
【Legal rule as primitive】penalty / standard / entitlement / enforcement: ___
【Tool chosen】framework / sufficient statistic / small structural model / fully solved model
【Key relation】estimand = f(estimable elasticities / parameters): ___
【Predictions derived before testing】[Y/N]
【Validity + what it omits】[...]
【Next step】jle-robustness