=Paper=
{{Paper
|id=Vol-2632/MIREL-19_paper_6
|storemode=property
|title=Reasoning with and about Factors in Statutory Interpretation
|pdfUrl=https://ceur-ws.org/Vol-2632/MIREL-19_paper_6.pdf
|volume=Vol-2632
|dblpUrl=https://dblp.org/rec/conf/jurix/AraszkiewiczZK19
}}
==Reasoning with and about Factors in Statutory Interpretation==
https://ceur-ws.org/Vol-2632/MIREL-19_paper_6.pdf
Reasoning with and about Factors in Statutory
Interpretation
Michal Araszkiewicz1[0000−0003−2524−3976] , Tomasz Żurek2[0000−0002−9129−3157] ,
and Blażej Kuźniacki3[0000−0002−3459−7656]
1
Department of Legal Theory, Faculty of Law and Administration, Jagiellonian
University, Kraków, Poland michal.araszkiewicz@uj.edu.pl
2
Institute of Computer Science, Maria Curie Sklodowska University, Ul. Akademicka
9, 20-033 Lublin, Poland tomasz.zurek@poczta.umcs.lublin.pl
3
Amsterdam Centre for Tax Law, University of Amsterdam
blazej.kuzniacki@gmail.com
Abstract. The main aim of this paper is to create a semi-formal model
of reasoning with cases in statutory interpretation. We introduce the
notion of reasoning protocol as a frame for a set of elements used by
relevant agents to justify their claims. Our model allows us to represent
reasoning not only with factors, but also about the relevance of factors
in deciding legal cases on the basis of statutory rules.
Keywords: Case-Based Reasoning · Statutory Interpretation · Factors·
Reasoning Protocol · Relevance.
1 Introduction
Hybrid reasoning with rules and cases has been the topic of interest for the AI
and Law community for more than two decades now, but it has been mostly
investigated in the context of Anglo-American law, which is hardly surprising
in the light of the significance of precedent in that particular legal environment
[14]. The problems of reasoning with factors in the context of application of
statutory law as it is understood in continental legal culture have recently be-
come a subject of interest, also because of the focus of the scientific community
on the problems of legal interpretation [16]. In this paper we outline a model of
legal reasoning concerning the interpretation of rules by means of factor-based
reasoning in the domain of the Polish tax law, which constitutes a good exam-
ple of rule-based domain rooted in the continental culture of statutory law. We
investigate how factors are used to develop statements concerning the interpre-
tation of law, and how a legal interpretation fixed in case law constrains the
reasoning of relevant agents for the future, even though no general stare decisis
principle applies in this context. We develop a notion of Reasoning Protocol – a
frame for a set of elements used by relevant agents to justify their claims about
Copyright c 2020 for this paper by its authors. Use permitted under Creative Com-
mons License Attribution 4.0 International (CC BY 4.0).
2 Michal Araszkiewicz et al.
the solution to legal problems. By using this tool we show on real-life examples
how legal problems are solved not by means of comparison of sets of factors, but
rather by deciding which factors are relevant in the first place.
The model presented in our paper has a descriptive character which means that
we do not introduce any mechanisms of argument creation or acceptance. In-
stead, we represent in a semi-formal manner the elements of reasoning that were
explicitly used in the actual wording of judicial opinions. It should be noted that
any loopholes and inconsequences of the parties’ reasoning, may cause the same
loopholes and inconsequences in their representation, which is the problem we
intend not to focus on, taking into account the assumed descriptive perspective.
2 Legal context
According to the Polish tax law, tax is levied on “net income” (dochód), which is
a surplus of total gross income (przychód) over the tax-deductible costs (article
7(2) of CITA [1]).The tax law stipulates that all costs incurred for the purpose
of obtaining, maintaining, or securing gross income are tax deductible, unless
otherwise explicitly provided by law (article 15(1) of [1]). Jurisprudence and tax
authorities clarify that there must to be a causal relationship between a cost in-
curred by a taxpayer and obtaining, maintaining, or securing gross income from
a given source of gross income. Thus, in order for a cost incurred by a taxpayer
to be a tax deductible cost, the following premises must be met cumulatively:
(i) the cost was incurred by the taxpayer; (ii) the cost remains in connection
with the business activity conducted by the taxpayer; (iii) the cost is definitive
(genuine) in the sense that the cost has not been returned to the taxpayer in
any way; (iv) the cost has been properly documented; (v) the cost was incurred
to obtain, maintain, or secure a source of gross income; (vi) and the cost is not
included in the closed-end catalogue of non-tax deductible costs in article 16(1)
of CITA. The conditions (i) to (v) are positive in the sense that they must occur
to qualify a cost as tax deductible, while the condition (vi) is negative, meaning
that it must not occur to qualify a cost as tax deductible. One of the categories
to be found in the catalogue of non-tax deductible costs are representation costs
(article 16 (1) (28) of the CITA). In practice it is often doubtful whether a par-
ticular cost falls under the category of representation cost.
Therefore, the taxpayer may often be interested to obtain an individual tax rul-
ing (ITR) resolving this problem (Art. 14b of the Tax Ordinance Act [2]). A
taxpayer who obtained an individual tax ruling is subject to legal protection in
the sense that the ruling contains the standpoint of the tax authorities on the is-
sue indicated in the ruling. An unfavourable individual advance tax ruling might
be challenged to the Voivodship Administrative Court (VAC) and subsequently
to the court of the second instance (SAC).
Reasoning with and about Factors in Statutory Interpretation 3
3 The basics of the model
Definition 1 (Language) Let L be a defined language being able to express
terms and standard logical and set-theory connectives (∨, ∧, ¬, ∈, etc. ) as well
as function symbols.
Definition 2 (Facts) Let C ⊂ L be a set of sets of propositions which represent
facts.
Definition 3 (Case facts) A set Ck = {c1 , ...cn } ⊂ C is referred to as case
facts, that is, the subset of C that constitutes the considered fact situation.
Definition 4 (Factor) Let F ⊂ L be a set of propositions representing factors.
By factors we understand propositions referring to elements of the case which
provide reasons for a decision for either party. Factors are often referred to as
“stereotypical fact patterns” to be distinguished from facts. Factors are binary
(they may be present in a given case Ck or not) and if they are present, they
always provide a reason for a decision for a given party. Superscripts we will
indicate the name of a party whose interest is supported by the existence of a
factor.
Similar to [3] we assume that factors may have various levels of abstraction and
lower level factors can be a basis of higher level factors’ acceptance.
Definition 5 (Classification statements) By sat(φ, fj ) ∈ L, where φ ∈ (C ∪
F ) we denote that a certain fact or ci or lower level factor can be classified as
factor fj . Let SAT be a set of all classification statements.
Definition 6 (Legal rule) Let ri be a legal rule i. Each rule is a pair ri =
hφ, ψi, where φ and ψ are a wff of L. φ is a condition of a rule and ψ is a
conclusion. By R we denote the set of all rules. By cond(r1) and conc(ri ) we
denote respectively condition and conclusion of a rule.
Definition 7 (Agents) Let IA ∈ L be a set of propositions representing names
of various agents in legal discourse. By iai ∈ IA we denote a given agent i.
Definition 8 (Interpretation) • ∈ L is a binary relation word denoting “is
interpreted as.” An in-depth discussion of the • functor can be found in [6]
Definition 9 (Interpretive statements) All expressions in the shape φ • ψ
where φ ∈ (F ∪ C), ψ = cond(ri ) and ri ∈ R will be referred to as interpretive
statements.
Definition 10 (Defined relations) Let REL ∈ L be a set of defined relations
between elements of L. For example:
– Strict Incompatibility – Let α and β be statements of a language L. The two
statements are strict incompatible SIN C(α, β) if they are incompatible and
while one of them is not accepted, then the second one must be accepted.
4 Michal Araszkiewicz et al.
– Conditional sufficiency – By SU F (fx , fy ) we denote that factor fx is, defea-
sibly, a sufficient condition for adoption of fy .
– Irrelevance – Let fi be a factor and rk a legal rule. By irr(fi , rk ) we denote
that factor fi is explicitly considered as irrelevant to interpretation of rule
rk .
– Relevance – Let fi be a factor and rk a legal rule. By rel(fi , rk ) we denote
that factor fi is relevant to interpretation of rule rk .
Definition 11 (Hypotheticals) H(φ) ∈ L, where φ is a wff of L, reads as
“hypothetically, φ”. Intuitively, if an agent makes an expression H(φ) this means
that the agent poses a hypothesis that φ might or may have been the case.
The expression −H(φ) ∈ L means that H(φ) is rejected. For any φ ∈ L, −H(φ)
iff ¬φ.
It is important to note that it is not the aim of this paper to reconstruct a logical
model of hypothetical or counterfactual thinking. The operator H is needed only
to distinguish the contexts “φ holds,” expressed simply as φ, from the contexts
like “φ might have been the case” expressed as H(φ).
Definition 12 (Argument) Let Aia i be an argument created by agent ia ∈ IA.
Each argument is a tuple Aia i = hname, Φ, ψi, where name ∈ L is an argument
name, Φ is a set of wff of L, and ψ is wff of L. Φ is a set premises of an argument,
ψ is a conclusion. By ARG we denote the set of all arguments. Intuitively by
Aia
i = hname, Φ, ψi, we denote that Φ supports ψ. By prem(name) ∈ L we
denote the set of premises of argument named name, by concl(name) ∈ L, and
author(name) ∈ L we will denote functions returning conclusion and author of
argument Aia ia
i : if Ai = hname, Φ, ψi, then prem(name) = Φ, concl(name) = ψ,
and author(name) = ia.
Definition 13 (Reasoning protocol) Let P ROTia = hname, Cl, Rs, Cf, Rf,
Rel, Cs, Sf, Is, Carg, Conci be a 11-tuple representing of reasoning protocol of
agent ia, where:
0. name ∈ L – is a name of the protocol;
1. Cl ∈ L – is a claim which agent ia is going to prove;
2. Rs ⊆ R – is a set of legal rules which agent ia needs to prove the claim;
3. Cf ⊂ C – is a set of case facts (actual state of affairs);
4. RRel ⊂ F – is a set of relevance relations of two kinds: rel(fi , rk ) and
irr(fi , rk );
5. ORel ⊂ L – is a set of other defined relations between factors (for example
incompatibility or strict incompatibility relations) which are relevant to the
case. We assume that in ORel can be used factors which are in the relations
from set RRel;
6. Cs ⊂ L – is a set of adopted classification statements;
7. Sf ⊂ F – is a set of satisfied factors i.e. factors which can be accepted (on
the basis of Cf );
8. Is – is a set of adopted interpretive statements;
Reasoning with and about Factors in Statutory Interpretation 5
9. Carg ⊂ ARG – is a set of subsumption arguments, i.e. arguments necessary
to support the conditional part of a legal rule;
10. Conc ∈ L – is a final conclusion, in most cases Conc = Cl.
Additionally we assume a set of functions returning particular sets of elements
of a protocol. For example, function Cl(name) ∈ L returns claim of protocol
named name.
Definition 14 (Case) Let CASEi ⊂ L be a case i represented by a set of
names of reasoning protocols used in the case. We assume that protocols in the
case are ordered. Let OCASEi ⊂ L be a partial order of elements of CASEi .
The order of protocols represents the power of the authors of particular reasoning
protocols over other authors. For example, a claim of tax authority (and its
arguments) is stronger than a claim of taxpayer; decision of a Court is stronger
than a claim of tax authority, etc. By CASE we denote the set of all cases.
The representation of a case is a key point of our model. The output of a previous
case includes not only the factors, rules and final decision, but also the more
extensive information represented in Reasoning Protocols. In a new case, the
Court, can construct an argument not only on the basis of the final decision,
but also on the basis of the mechanisms used in arguments justifying a previous
decisions.
4 The case
We use the model outlined in the previous section to represent the reasoning of
relevant agents in two cases, namely, the judgment of 7 judges panel of the SAC
of 17 June 2013 (II FSK 702/11, hereafter: Judgment 1) and the judgment of
the VAC of Rzeszów of 23 October 2018 (I SA/Rz 741/18, hereafter: Judgment
2). Judgment 1 is particularly interesting because the SAC expressed an opinion
on the appropriate interpretation of the statutory rule concerning the costs of
representation. The modelling of Judgment 2 shows how the preceding decision
practically constrains the legal reasoning of relevant agents even though no stare
decisis principle is applicable in this context.
Judgment 1
The legal context for the case is provided by the statutory rule r1, based on art.
16.1.28 of the CITA as discussed above in Section 2:
cond(r1) = representation costs including costs related to purchase of
catering services or f ood or beverages including alcoholic ones
conc(r1) = not tax − deductible costs
In the case that gave grounds for Judgment 1, the agent taxpayer (TP) was
interested to obtain an ITR to the effect that the costs incurred by TP are
not representation costs (the positive conditions of tax-deductible costs were as-
sumed to be met). In the motion for ITR, TP outlined a hypothetical case C1
comprising the facts that TP, being a company, organizes business meetings with
its (potential) contractors and incurs the purchase of catering services. The sig-
nificant catering expenses are incurred when meetings take place in restaurants,
6 Michal Araszkiewicz et al.
so the significant facts may be presented as follows:
C1 = {c1, c2} where c1 = business meetings in restaurants,
c2 = taxpayer incurs catering expenses During the time the motion of ITR
was filed, the case law, concerning what factors should be considered in the pro-
cess of qualification of a given cost as an instance of representation cost, was
unstable. This state of affairs gave rise to proceedings before the Tax Authority,
The Voivodeship Administrative Court and the Supreme Administrative Court,
which eventually referred the case to be decided by the grand jury (7 judges
panel).
The SAC was considering whether the legal rule r1 (category Rs) should be ap-
plicable to the presented case facts (Cf ). Unlike in the previous case law (which
we do not discuss here because of space limitations), the SAC stated the factor
relevant for deciding whether a given cost is a representation cost: the exclu-
sive or main goal of this cost must be the building of image by the taxpayer. If
this factor is not met, the tax authorities should assume that the cost was met
for business purposes (provided that the positive conditions of tax deductibility
were met, which was assumed in the present case). In a given case SAC recog-
nizes two relevant factors: f1 = image building exclusive or main purposeT A
and f2 = business purposeT P , while category (ORel) defines the strict incom-
patibility relation between them. In the context of the case facts the court held
that the factor f1 should not be considered to apply only because the meetings
took place in restaurants or because they involved the purchase of catering. The
adoption of f1 as the only factor relevant for the interpretation of the rule condi-
tion imposes a degree of argumentative burden on tax authorities: it is difficult
to sufficiently argue that the cost of image building as its exclusive or main goal.
The interpretive standards adopted by the SAC, in particular in judgments en-
acted by the grand jury, are practically difficult to challenge, taking into account
that if properly complained, the future case will eventually be heard by the SAC.
The Reasoning Protocol of the SAC (SAC judg1 ∈ CASESAC judg1 ) may be
presented as follows.
Category Content
name SAC judg1
Cl ¬conc(r1)
Rs r1
Cf C1 = {c1, c2}
RRel rel(f1 , r1), rel(f2 , r1)
ORel SIN C(f1 , f2 )
Cs S1 = ¬sat(C1, f1 ), S2 = sat(C1, f2 )
Sf f2
Is IS1 = f1 • cond(r1)
Carg Asac1 =< a1, {IS1, ¬f1 , f2 }, ¬cond(r1) >
Conc ¬conc(r1)
Judgment 2
In the fact situation that gave rise to the issuance of Judgment 2, the TP ap-
plied for an ITR concerning the following circumstances: the TP acting as a
Reasoning with and about Factors in Statutory Interpretation 7
company (employer) organizes integration events both for its workers employed
on the basis of employment contract and for its B2B contractors. The organi-
zation of the integration events requires purchase of catering services for the
participants. The TP argues that such costs do not amount to representation
costs. However, the TA disagreed with the TP with regard to the costs re-
lated to participation of B2B contractors on the basis that they are actually
third parties. The set of relevant case facts includes one element: C2 = {c3},
c3 = intergration events f or B2B contractors
Category Content
name T P judg2
Cl ¬conc(r1)
Rs r1
Cf C2
RRel rel(f1 , r1), rel(f2 , r1)
ORel SIN C(f1 , f2 )
Cs S3 = ¬sat(C2, f1 ),
Sf f2
Is IS1 = f1 • cond(r1)
Carg Atp 2 =< a2, {IS1, ¬f1 , f2 }, ¬cond(r1) >
Conc ¬conc(r1)
As we can easily ascertain, the TP followed strictly the Reasoning Protocol
employed by the SAC in Judgment 1. Obviously, the case facts that gave rise
for the motion for the ITR were different, but the TP adopted relevant fac-
tors (RRel) and the defined relation (ORel) in accordance with the Reasoning
Protocol SAC II FSK 702/11. The TA basically followed the Reasoning Proto-
col designed by the SAC in the II FSK 702/11 case (Judgment 1) because it
adopted the same interpretive statement and it also did not reject any of the
factors accepted by the SAC. However, the TA also added an additional factor
and additional relation between factors. The TA conceded that the B2B con-
tractors are third parties with regard to TP, and that the existence of such a
factor implies the existence of the factor f4 , that is, if the newly designed factor
is satisfied, the f4 factor is also satisfied. The factor designed by the TA may be
represented as follows: f1.1 = costs incurred f or the third party T A
Since the factor f1.1 is attached to f1 as an immediate lower-level factor, there
is a relation SU F (f1.1 , f1 ) between them. The Reasoning Protocol of the TA:
8 Michal Araszkiewicz et al.
Category Content
name T A judg2
Cl conc(r1)
Rs r1
Cf C2
RRel rel(f1 , r1), rel(f2 , r1), rel(f1.1 , r1)
ORel SIN C(f1 , f2 ), SU F (f1.1 , f1 )
Cf S4 = sat(C2, f1.1 ), S5 = sat(f1.1 , f1 ),
Fs f1.1 , f1
Is IS1 = f1 • cond(r1)
Carg Ata3 =< a3, {IS3, f1.1 , f1 }, cond(r1) >
Conc conc(r1)
As we can see, the TA did not delete any information from the categories RRel,
ORel, or Is from Reasoning Protocol as designed by the SAC in Judgment 1,
but instead attempted to develop it by establishing a new factor f1.1 understood
as a sufficient condition for adoption of f1 .
The TP filed a complaint to the VAC. The VAC agreed with the TP and applied
legal meta-reasoning by pointing out that the TA had introduced an inappropri-
ate standard. The Reasoning Protocol developed by the VAC was identical to
the one employed by the TP, so instead of repeating it here, let us reconstruct
the meta-argument based on the discrepancy of the Reasoning Protocol the TA
was supposed to use and the Reasoning Protocol it actually used.
Category Content
name V AC judg2
Cl ¬conc(r1)
Rs r1
Cf C2
RRel rel(f1 , r1), rel(f2 , r1), irr(f1.1 , r1)
ORel SIN C(f1 , f2 )
Cf S6 = ¬sat(C2, f1 ), S7 = sat(C1, f1.1 ),
Fs f2
Is IS1 = f1 • cond(r1)
Carg Avac
4 =< a4, {H(rel(f1.1 , f1 ) ∈ RRel(SAC judg1))},
S7 ∈ Cs(SAC judg1) >
Avac
5 =< a5, {¬(S7 ∈ Cs(SAC judg1),
inc(¬(S7 ∈ Cs(SAC judg1)), H(rel(f1.1 , f1 ) ∈ RRel(SAC judg1))},
−H(rel(f1.1 , f1 ) ∈ RRel(SAC judg1))
Avac
6 =< a6, {−H(rel(f1.1 , f1 ) ∈ RRel(SAC judg1)))},
¬(rel(f1.1 , r1) ∈ RRel(SAC judg1)) >
Avac
7 =< a7, {¬rel(f1.1 , r1) ∈ RRel(SAC judg1)}, irr(f1.1 , r1) >
Avac
8 =< a8, {irr(f1.1 , r1), f1.1 ∈ prem(a3), r1 ∈ Rs(T A judg2),
a3 ∈ Carg(T A judg2)}, ¬a3 >
Avac
9 =< a9, {IS1, ¬f1 , f2 }, ¬cond(r1) >
Conc ¬conc(r1)
The VAC basically agreed with the TP and disregarded the reasoning of the TA,
Reasoning with and about Factors in Statutory Interpretation 9
which led to avoiding of the ITR provided by the latter agent. One can notice
that TA did not go straightforwardly against the Reasoning Protocol designed
by the SAC, but added new elements to its arguments (factor f1.1 , the relation
SU F (f1.1 , f1 )), effectively narrowing the scope of tax-deductible costs. On the
first sight, such an extension of the set of relevant elements was not precluded
by the SAC. The VAC provided an additional argument for its position by using
the SAC’s opinion to justify that the Reasoning Protocol developed by the TA
was fallacious. The argument of the VAC is based on hypothetical reasoning.
First, the VAC indicates that if the SAC considered f1.1 to a be a relevant factor
for interpretation of the rule r1, it would also have held that the factor f1.1 was
satisfied by the case C1, because obviously, the meetings in restaurants in C1
were organized for third parties (a4). Because, such a classification statement
was not recognized by the SAC, the hypothetical statement that the f1.1 would
be the relevant factor should be falsified (a5). On this basis, the VAC drew an
explicit conclusion that the factor f1.1 is not relevant for the interpretation of
the rule (a6) and therefore it is irrelevant in this context (a7). The argument
a7 attacks one of the premises of the TA’s argument a3, which invalidates the
latter agent’s reasoning.
The set CASEjudg2 = {T P judg2, T A judg2, V ACjudg2 } contains all reason-
ing protocols of all parties which take part in the discourse. Both T P judg2
and V ACjudg2 have the same conclusion (¬cond(r1)), which is in conflict with
the conclusion of T A judg2 (cond(r1)). We also assume that the Court has
power over both parties which can be represented by order OCASEjudg2 =
(V ACjudg2 > T P judg2), (V ACjudg2 > T A judg2), thanks to which the Court’s
conclusion prevails over the conclusion of the Tax Authority.
5 Discussion
This paper has two main contributions. The first one is the development of the
notion of Reasoning Protocol and the second one is the investigation of selected
patterns of case-based judicial reasoning in the context of statutory interpreta-
tion as it is understood in continental legal culture. We investigated cases where
not only factors played a role in forming interpretive sentences, but also where
reasoning about the relevance of factor played a pivotal role in judicial reasoning.
The Reasoning Protocol is a tool for descriptive systematization of legal reason-
ing. It does not aim, per se, to be a computational model of legal argument, but
rather a means to systematize the elements of reasoning explicitly used in the
text of judicial opinions. Therefore, it is designed first and foremost to study
past decisions and to systematize knowledge about the reasoning patterns used
in legal practice, not only by courts, but also by other agents whose reasoning is
reported in judicial opinions. The Reasoning Protocol is designed to represent in-
complete, enthymematic reasoning. However, it may serve as a starting point for
reconstruction of premises that are further used to feed computational models of
legal reasoning.The second contribution of the paper is the investigation into the
structure of reasoning with cases in the continental legal culture environment.
10 Michal Araszkiewicz et al.
Whilst the problem of justifying legal interpretation with different classes of ar-
guments (linguistic, systemic, and functional) has already earned considerable
attention from the AI and Law community, the role of factor-based reasoning
in this context, analyzed from the descriptive point of view, has remained ne-
glected. In this contribution we have purposefully focused on the problem how
the determination of factors in a landmark case (Judgment 1) influenced the
reasoning in a following case (Judgment 2). We have investigated how the Tax
Authority attempted to narrow the scope of interpretation of the notion of tax-
deductible costs by introducing new elements to the Reasoning Protocol content
fixed by the SAC, and how the VAC criticized this attempt by constructing and
applying a complex hypothetical argument. The analysis reveals important par-
allelism between common-law case-based reasoning on the one hand and civil
law case -based reasoning on the other hand. In both contexts (1) hypotheti-
cal reasoning is important in the context of case-based reasoning and (2) the
relevant agents may attempt to draw consequences from the features that dis-
tinguish the present case from the previous one. The use of the hypothetical
reasoning has revealed an important and methodologically challenging issue: the
TA attempted to build its argument on assumed information that might have
been implicit in the leading case decided by the SAC. The new case was based on
a different set of case facts, which might have lead to satisfaction of different set
of factors. However, the crucial issue was whether the factor “discovered” by the
TA (f1.1 ) was legally relevant in this context at all. Testing these assumptions
led the VAC to the conclusion that the reasoning of the TA was fallacious. The
TA added unfounded information to the Reasoning Protocol and thus followed a
wrong Reasoning Protocol which lead to avoidance of its decision (ITR). In order
to focus on the phenomenon described above, we have purposefully ommitted
the issues of interpretive argumentation [5], [16] and reasoning with values [17],
[18], [15], [9]. Also, we have employed the notion of binary factors [4] as opposed
to dimensions [7] or recently debated notion of factors with magnitudes [12],
[10]. The Reasoning Protocol conception is able to accommodate these different
approaches to modeling of case-based knowledge.
6 Conclusions and future work
This paper shows how reasoning with and about factors in the context of statu-
tory interpretation may be described with a tool referred to as Reasoning Pro-
tocol. This tool enables researchers to systematize and compare the reasoning
used by different agents that arguing in legal cases. With this tool, we have
analyzed how factors are used in statutory interpretation and how the issue of
factor relevance is addressed in this context. In the discussed example, the fac-
tors provided the basis for formulation of interpretive statements. We have also
shown how the relevance of certain factors is argued in the context of statutory
interpretation and how hypothetical argumentation is used to justify the conclu-
sions in this area. As for the directions of further research, three of them should
be mentioned. First, we intend to broaden the scope of analyzed cases and the
Reasoning with and about Factors in Statutory Interpretation 11
information represented in the Reasoning Protocol. The scope of information
represented in the Reasoning Protocol will be extended to encompass, inter alia,
the interpretive arguments and value-based reasoning. The adopted methodol-
ogy will be also applied in other domains of law, to evaluate the generalizability
of the present approach. It is also not excluded that the analysis of a broader
set of cases will enable the use of more complex types of case-based reasoning
knowledge representation, such as factors with magnitudes or dimensions. Sec-
ond, the information and reasoning patterns found in Reasoning Protocols may
be integrated with a methodologically different approach, that is, computational
modelling of legal argument, enabling automation of reasoning, in such systems
as ASPIC+ [13] or Carneades [11]. The Reasoning Protocols may serve as a
source of premises for such models and in this context the enthymematic infor-
mation not represented in the Protocols should be reconstructed.Such a study
may provide insights as to the types of information that are left implicit in ju-
dicial opinions, as well as in different deficiencies of the actual reasoning (such
as incosistencies, inconsequences, loopholes). As for the third direction, Reason-
ing Protocols may be fruitfully used for the development of data sets of cases,
aiming at providing statistical information about the elements of legal reasoning
which can be useful for predicting of outcomes of cases and in information and
argument retrieval [8]. The Reasoning Protocol may be used as an outset for the
development of a case annotation scheme.
Acknowledgments
The work of Michal Araszkiewicz and Tomasz Żurek was part of the project
“Legislative errors and the comprehensibility of legal texts” financially supported
by the National Science Centre; agreement no. UMO-2018/29/B/HS5/01433
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