Towards Modeling
Systematic Interpretation of
Codified Law
Matthias Grabmair
University of Augsburg School of Law
Germany
Kevin D. Ashley
University of Pittsburgh School of Law
Intelligent Systems Program
USA
http://www.plainreasoning.com
M. Grabmair & K. D. Ashley
Towards Systematic Interpretation of Codified Law
Jurix Conference 2005
Systematic Interpretation

... is one of the four recognized civil law interpretation
methods besides wording, legislative intent and teleology.

... analyzes a norm with respect to its position in the code’s
overall structure and interconnected meaning.
[Larenz, 1995; Alexy 1978]

... means interpretation of norm interaction.

The norm is interpreted in light of the influence of other norms ...

... and in light of the influence the norm has on its surrounding ones ...

... in its Sphere of Influence.
M. Grabmair & K. D. Ashley
Towards Systematic Interpretation of Codified Law
Jurix Conference 2005
2
Legal Sentences


Complete Legal Sentences [Larenz, 1995]

... form a regulation by themselves because they mention all their
requirements and consequences.

... can directly be translated into an IF-THEN relation.
Incomplete Legal Sentences

... need to be read in conjunction with other legal sentences in order
to construe an autonomous regulation.

... need systematic interpretation in order to be translated into an IFTHEN relation.
M. Grabmair & K. D. Ashley
Towards Systematic Interpretation of Codified Law
Jurix Conference 2005
3
Point of Departure
How can a piece of written law be translated into a ruleset
and, at the same time, capture the systematic interplay of its
legal sentences authentically?
M. Grabmair & K. D. Ashley
Towards Systematic Interpretation of Codified Law
Jurix Conference 2005
4
The Approach in a Nutshell
INR
Code
IF-THEN relations
with Interaction
Predicates in
isomorphic original
code structure
Generation
Rulebase
Plain final rules
Domain
Knowledge
Ontologies
M. Grabmair & K. D. Ashley
Towards Systematic Interpretation of Codified Law
Jurix Conference 2005
5
INR

The Intermediate Norm Representation (INR) mirrors the code in
its original structure in an isomorphic way using IF-THEN
relations. [Prakken & Schrickx, 1994]

No exterior information is used in formulating a relation from the
original legal sentence.

Hooks for norm interaction and the sphere of influence are
neutrally preserved through the use of Interaction Predicates.
M. Grabmair & K. D. Ashley
Towards Systematic Interpretation of Codified Law
Jurix Conference 2005
6
Interaction Predicates

... are used in the INR in the same way as standard binary
predicates.

... symbolize standardized phenomena of norm interaction (e.g.
referrals, exceptions, etc.)

... are equipped with encapsulated reasoning algorithms that are
defined at the outset as the typical reasoning steps a jurist
undertakes when encountering the respective norm interaction.

The algorithms use code structure and domain knowledge
ontologies to generate final, unambiguous rulesets and arrange
them in a tree. [Gardner, 1987]

Conflicts can be detected [van Engers et. al., 2000] and solved through
authentic legal reasoning.
M. Grabmair & K. D. Ashley
Towards Systematic Interpretation of Codified Law
Jurix Conference 2005
7
Example
§1 “For c, r1, r2 and r3 need to be fulfilled.”
INR:
Ruleset:
IF (r1 AND r2 AND r3) THEN c
IF (r1 AND r2 AND r3) THEN c
§2 “In case of r4, r3 shall suffice.”
INR:
IF (r4) THEN suffice(r3)
Reasoning of the suffice-Interaction Predicate:
 §1 is determined as referenced norm out of the structure.
 Domain knowledge is used to determine implicit assumptions.
 Most plausible interpretation(s) spread out a ruleset tree.
Ruleset (e.g.):
IF (r1 AND r3 AND r4) THEN c
M. Grabmair & K. D. Ashley
Towards Systematic Interpretation of Codified Law
Jurix Conference 2005
8
Core Concepts
§1
Ruleset Tree
§§1,2
§§1,2,3
Sphere of
Influence
Each node is a complete
ruleset from the same static
INR and inherits its mother
node interpretations.
The set of norms a certain
norm influences and by
which it is influenced.
M. Grabmair & K. D. Ashley
Towards Systematic Interpretation of Codified Law
Jurix Conference 2005
9
Further Challenges
 Issues


Strong dependency on the definitions of ontologies and
predicates
Risk of oversensitivity, but necessary to capture subtleties
 Project Aims



Contribute to norm interpretation research in AI&Law
Sharpen contours of legal methodology through experiment
results
Correctly visualize a norm’s sphere of influence in the code
 State of the Project


In the phase of conceptualization
Search for a suitable legal test field for a future experiment
M. Grabmair & K. D. Ashley
Towards Systematic Interpretation of Codified Law
Jurix Conference 2005
10
Thank You!
Slides available at:
http://www.plainreasoning.com
M. Grabmair & K. D. Ashley
Towards Systematic Interpretation of Codified Law
Jurix Conference 2005
11