Mixing Legal and Non-legal Norms
Alexander Boer
aboer@uva.nl
Overview
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The ontological status of norms
Why norms as preferences?
Validity of norms as preferences
 Contrary-to-duty situations
 Normative conflict
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Further work
Only in the paper
 Composition of non-legal preferences vs.
 Composition of legal preferences (choice
principles)
The ontological status of norms

‘Norm’ is an epistemological category in
assessment
 Of a broken circuit board (norm group)
 Of abnormal behaviour (normal)
 Of undesirable behaviour (normative)
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‘Preference’ is an epistemological category
in planning
 Personal preference
 Adopted preference (constraint)
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In context of agent: norm = preference
Norms and Preferences in the Legal System
1. ‘Norms of analysis’ of involved
stakeholders in drafting legislation
2. Legal norms adopted from legislation by
addressees of legislation
3. Social norms adopted by addressees of
legislation
4. Personal preferences of addressees
5. Adaptation of personal and social
preferences to legal norms (evasion)
Uses of preferences
Making decisions constrained by legal
norms (Legal Services Counter, E-POWER)
 Assessing behaviour against legal norms
(CLIME)
 Assessing expected behaviour (adapted to
legal norms) against ‘norms of analysis’ (EPOWER simulation)
 Comparing two alternative sets of legal
norms (E-POWER simulation)
 Almost always legal and non-legal
preferences involved
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Why?
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My PhD Thesis
Newton workbench
 Understandable Legal Knowledge Acquisition
 Understandable representation method
 Semantic Web (merging norms from different
sources)

ESTRELLA Project

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European project for Standardized Transparent
Representations in order to Extend LegaL Accessibility
Legal Knowledge Interchange Format (LKIF)
Make everybody happy: represent whatever you want,
apply reasoning rules depending on purpose
Ideas
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Entity-Relationship-based (boxes and lines)
method for representing normative
statements in the Web Ontology Language
(OWL)
Use mainstream Decision Theory concepts
(choice, preference, composition of
preferences)
 Mixing with non-legal preferences

Use concepts from Knowledge Acquisition
methodology
 Concept Triads and decision trees/tables
Knowledge Acquisition as eliciting choices
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Ontology and Decision Trees
 Concepts and differentiae
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Repertory grids
 Triads: Binary choices, opposites
 Choice reveals a preference
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Norms
 Binary choice between compliance and
violation
 Choice is guided by imposed preference
(acceptance of a norm)
Norms as preferences?
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Revealed vs. motivating preference
Preference for things vs. classes of things
Combinative vs. exclusionary preference
Conditional vs. absolute preferences?
S
subClassOf
A
disjointWith
<
¬A
Subsumption
Conditional preference
Deontic operators to preference relations
A fourth deontic operator: Liberty
Representation in OWL
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Entity-relation model (subject-predicateobject triples)
Very similar to description logics (KIF,
LOOM, KRSS, etc.) but very different
(graph-based) syntax
Separates statements about concepts
(terminology) and instances (assertions)
No Unique Name Assumption for instances
Merging triples from different sources
Preference for classes of things in OWL
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Operational semantics of preference
relation is similar to =, =<, >=, >, <
Relation on concepts, not instances
 Second order relation
 Either not OWL DL but OWL Full, or two
separate OWL DL terminological boxes
 “Second order Reasoning” in practice simple

Not possible to represent that = and < are
disjoint!
 No disjointness on relations…
>=
=<
<
=
>
Validity of norms as preferences?
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Contrary-to-duty situations
 Chisholm, Forrester, Gentle Murderer,
Reykjavic, etc.
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Normative conflict
 Conflict of disaffirmation
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Disaffirming an imperative
Disaffirming a permission
Hill’s ‘intersection’ conflicts
 Conflict of compliance
 Other conflicts
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Hohfeldian concepts, etc.
Contrary-to-duty situations
Chisholm’s situation
Chisholm’s situation
The Reykjavic situation
Normative Conflict
Conflicts of disaffirmation: disaffirmation of an imperative
Using the network facilities in the university building is
prohibited.
Using WiFi in the classrooms is permitted.
Conflicts of disaffirmation: disaffirmation of a permission
Using the network facilities in the university building is permitted.
Using WiFi in the classrooms is prohibited.
Unresolved cases of disaffirmation
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Symmetric subsumption of situation vs.
alternatives:
 Using the network facilities in the classrooms is
prohibited.
 Using WiFi in the university building is
permitted.

No clear solution:
 Is this simply not a conflict?
 Does the most specific description of
alternative take precedence?
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Hill’s “intersection conflicts”?
Unresolved cases of disaffirmation
Conflicts of compliance
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‘Impossibility of joint compliance’ (IJC)
In S you ought to both P and not P
 Did you voluntarily enter into situation S?
 Can you move out of situation S?
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Example:
 Police: night clubs ought to lock unguarded
emergency exits
 Fire department: night clubs ought not to lock
emergency exits
Conflicts of compliance
Conflict between permissions?
Elhag et al:
“There seem to be other types of conflict as that
between the permission for A to live in a
certain house and a permission for B to destroy
that same house. These conflicts need our
attention and have to be embodied in a theory
on normative conflicts.”
1. Neither agent has to deal with a circular ordering
of alternatives
2. Both agents are free to act
Other cases of conflict?
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Conflict of legal and non-legal norms
 permission for A to live in a certain house and a
permission for B to destroy that same house 
 permission for A to live in a house that is to be
destroyed (given B’s preferences?)
 A norm of analysis is violated…
 Alternative: assumption of implicit right-duty
relation between A and B?
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Conflict of a norm with reality
 Unrealizability of compliance with norm
Other work

Composition of preferences in Law vs.
Decision Theory
 Choice rules (Lex Specialis etc.) work because
of restricted format for legal preferences
 Additive (MAUT) and multiplicative (utility)
composition in Decision Theory
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Hohfeldian legal concepts
 Right, duty, power, liability, etc.
Further work
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ESTRELLA’s LKIF and Newton
Axioms on/off
 Automated Problem Solving vs. evaluation
queries
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Isomorphism MetaLex legislative XML
structures to OWL representation
 Classification of sentence patterns
 Normative statements about (application of)
legislation
 Choice rules defined in legislation
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E.g. overruling Lex Posterior