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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>A Legal Validation of a Formal Representation of GDPR Articles</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Cesare Bartolini</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Gabriele Lenzini</string-name>
          <email>gabriele.lenzinig@uni.lu</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Cristiana Santos</string-name>
          <email>cristiana.teixeirasantos@gmail.com</email>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>University of Luxembourg, Interdisciplinary Centre for Security</institution>
          ,
          <addr-line>Reliability and Trust, SnT</addr-line>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>University of Minho</institution>
          ,
          <addr-line>JusGov</addr-line>
        </aff>
      </contrib-group>
      <fpage>111</fpage>
      <lpage>124</lpage>
      <abstract>
        <p>It is possible to model the meaning of articles of the GDPR in logic formul and this enables a semi-automatic reasoning over the Regulation, e.g., to build an argument of compliance. However, any formal reasoning requires that the formul are validly expressing the legal meaning(s) of the articles, including potential disagreements between legal experts over their interpretation. The problem is that IT experts may anticipate some uno cial legal meaning, invalid under any interpretation, while verifying if this happens requires legal expertise. However, legal experts are unlikely familiar with the logic formalism and cannot give informed feedback without understanding the legal interpretation(s) that a formula embodies. On a previous work, we devised a methodology and a human-readable intermediate representation to help non-experts reading formul in Rei ed I/O logic (RIO), a formalism expressing GDPR provisions introduced to reason about data protection compliance. This paper validates the methodology and shows that is possible to retrieve feedback from legal experts about the validity the RIO representation of the Regulation. Precisely, we collect and evaluate the feedback on the RIO version of Art. 5.1a and Art. 7.1, and show how to elicit suggestions to improve the formalization thereof. What emerges is an agile process to support public trust in the formal framework and in its use.</p>
      </abstract>
      <kwd-group>
        <kwd>General Data Protection Regulation (GDPR)</kwd>
        <kwd>data protection</kwd>
        <kwd>compliance</kwd>
        <kwd>legal validation</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>-</title>
      <p>The processing of personal data { and therefore data protection legislation {
is an essential facet of a modern economy. Personal data is widely associated
with a modern business model made of Internet-based services o ered free of
charge and whose revenues come from the collection, the processing and the use
of personal data for advertising purposes, but it comes into play also with more
traditional business models, such as the product market, which are evolving to
e-commerce, or tailoring their o ers to individual customers.</p>
      <p>
        The legal landscape of the protection of personal data within and outside the
European Union (EU) has been redesigned by the amplitude of the material and
territorial scope of the General Data Protection Regulation (GDPR) [
        <xref ref-type="bibr" rid="ref21 ref25 ref5">5,25,21</xref>
        ],
as had already happened, to some extent, with the previous Directive [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ].
      </p>
      <p>This new landscape, coupled with the heavy nes that supervisory
authorities are entitled to issue in case of violation, calls for a need to ensure that
data processing activities (and tools thereof) comply with the GDPR. Data
controllers and processors could therefore take advantage from tools helping design
and verify compliance, thus diminishing their risks of violating provisions and
incurring into nes. Such tools could also help companies build, in an automated
or computer-assisted way, their case in response to one-time casuistic decisions
emanated by supervisory authorities and courts against them.</p>
      <p>
        A critical facet for such automation is to be able to build executable rules
for a computer-assisted assessing compliance. In previous research, the authors
have proposed a complete model of the GDPR for legal reasoning and legal
compliance [
        <xref ref-type="bibr" rid="ref1 ref15 ref16 ref17">1,17,16,15</xref>
        ]. This model comprises three components: the legal text
in Akoma Ntoso format, an ontology of legal concepts concerning privacy and
data protection, and a knowledge base of data protection rules in LegalRuleML
format. This last component, called the Data Protection Regulation
Compliance (DAPRECO) Knowledge Bas Knowledge Base, is the most critical: it
contains the bulk of provisions written as logic rules that can be used e.g., to check
whether certain practices (themselves also formalized) are aligned with the
provisions. Consequently, the Knowledge Base needs to be adequately (i.e., legally)
validated before it can perform in a real-world environment. This
pragmatical strand is demanded, since \for developers, as contrasted to researchers, the
issue is not whether the resulting rule base is complete or even accurate or
selfmodifying { but whether the rule base is su ciently accurate to be useful" [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ]
when it is moved out from the research laboratory and into the marketplace [
        <xref ref-type="bibr" rid="ref24">24</xref>
        ].
      </p>
      <p>
        However, as is widely acknowledged in literature [
        <xref ref-type="bibr" rid="ref11 ref19 ref23">19,23,11</xref>
        ], testing Legal
Knowledge Based System (LKBS) is a di cult task. It is more di cult even than
software testing in general because approaches reveal coder-dependency and it
is complex to emulate the \art-of-the-experts" [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ]. With ongoing maturity in the
eld of AI and Law and Legal Knowledge-Based Systems, the need for an easily
accessible and interdisciplinary validation methodology comes into play [
        <xref ref-type="bibr" rid="ref10">10</xref>
        ].
      </p>
      <p>
        The concept of validation refers to the determination of the correctness of the
system with respect to user needs and requirements [
        <xref ref-type="bibr" rid="ref23">23</xref>
        ]. Legal validation is thus
\needed to verify the correctness of the output of the system in relation to the
knowledge of the legal domain it covers", \the guarantee of the one-to-one
relation between analysis and representation" [
        <xref ref-type="bibr" rid="ref12">12</xref>
        ]. Such a method would assist legal
professionals framing an evaluation of legal knowledge-based systems and help
IT experts understanding the validation requirements of legal professionals [
        <xref ref-type="bibr" rid="ref11">11</xref>
        ].
      </p>
      <p>
        As \algorithmic representations of law are typically very poor as regards
their transparency", \one cannot begin to devise an algorithm to apply legal
provisions without determining rst its intended purpose and by whom it will
be used" [
        <xref ref-type="bibr" rid="ref22">22</xref>
        ]. Therefore, validating a legal model requires that the formalization
used is understandable, accessible. Consequently, the methodology should be
driven by usability considerations in the adopted criteria, and validation tests
(through user acceptance surveys or questionnaires) [
        <xref ref-type="bibr" rid="ref23">23</xref>
        ].
      </p>
      <p>
        In the particular domain of modelling the GDPR, a considerable e ort has
been reserved to represent the Regulation's provision in a logic formalism,
precisely the Rei ed Input/Output (RIO) logic [
        <xref ref-type="bibr" rid="ref20">20</xref>
        ]. As we will recall in Section 3,
the logic formul refer to concepts that belong to a legal ontology for data
protection, that is, the Privacy Ontology (PrOnto) ontology which is the
result from an interdisciplinary e ort meant to provide legal soundness. But of
course referring to an ontology is not su cient to ensure legal soundness in a
reasoning process for many reasons, among which that the ontology has been
devised for concepts relevant in data privacy but not for the speci c context of
the GDPR and thus new concepts may need to be expressed; besides, certain
legal interpretation are anticipated e.g., in the choice of the formula's functions
or when deciding that certain articles express an obligation or a permission. We
will discuss further the critical points of a formalization exercise but, in short, it
should be evident that formalizing articles in a logic formalism requires a legal
supervision. Postponing any legal validation until the whole GDPR is translated
into RIO formul , as it would happen if we were awaiting to have any output
of the enabled logical reasoning, is a procedure prone to errors. Finding and
removing the cause of some unsound conclusions would be also a very expensive
step if left only at the end, quite likely inspiring distrust in the whole framework.
A more agile process is advisable to verify for legal soundness, assisting who is
responsible for the formalisation of the GDPR incrementally and concomitantly
during the modelling work.
      </p>
      <p>
        Pursuant to this, we discussed in [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ] such an agile methodology, proposing also
a solution for a further problem that arose in this case: how to let expert in law
understand the logic formula, which are usually embedded in a machine readable
but quite human incomprehensible LegalRuleML, in such a way to collect
informed feedback from them about the legal soundness of the formalization. The
solution is an intermediate representations, devised human-readable, of a RIO
logic formalization of two GDPR articles. A usability experiment involving
legal domain experts, consisting in assessing the readability and understandability
of the human-readable representation compared with the original LegalRuleML
version and with another control format, brought evidence that the former suits
the purpose of being used for an interdisciplinary legal validation.
      </p>
      <p>The customizable human-readable representation has been assessed as
understandable, increasing our con dence on it being an eligible candidate to validate
the formalized GDPR articles. In this work we proceed further and show that
the methodology is e ective in gathering feedback of legal experts on the legal
validity of the representation of the GDPR articles, so as to provide quality
assurance of our methodology as a whole.</p>
    </sec>
    <sec id="sec-2">
      <title>Related work</title>
      <p>
        Some discussion within the AI and Law community [
        <xref ref-type="bibr" rid="ref10 ref11 ref23">23,11,10</xref>
        ] { speci cally
amidst the Proceedings of the International Conference on Arti cial Intelligence
and Law works (ICAIL), and later through the Journal of Arti cial Intelligence
and Law contributions (JAIL), { concerned qualitative evaluation methodologies
suitable for legal domain systems/techniques, and the best practices through
which AI and Law researchers could frame the assessment of the performance
of their works, both empirical and theoretical. For example, performance
evaluation is emphasized and compared to known baselines and parameters, using
publicly available datasets whenever possible [
        <xref ref-type="bibr" rid="ref7 ref8">7,8</xref>
        ].
      </p>
      <p>A set of six categories was compiled to de ne the broad types of evaluation
found therefrom. They include the following assessments: i. Gold Data:
evaluation performed with respect to domain expert judgments (e.g., classi cation
measurements or measures on accuracy, precision, recall, F-score, etc.); ii.
Statistical : evaluation performed with respect to comparison functions (e.g.,
unsupervised learning: cluster internal-similarity, cosine similarity, etc.); iii. Manual
Assessment : performance is measured by humans via inspection, assessment,
review of output; iv. Algorithmic: assessment made in terms of performance of a
system, such as a multi-agent system; v. Operational-Usability : assessment of a
system's operational characteristics or usability aspects; vi. Other : those systems
with distinct forms of evaluation not covered in the categories above (task-based,
conversion-based, etc.). In our case, we combined the following types of
evaluation: gold data (i.), manual assessment (iii.) and operational-usability (v.).</p>
      <p>
        Some authors [
        <xref ref-type="bibr" rid="ref10">10</xref>
        ] developed the Context Criteria Contingency-guidelines
Framework (CCCF) for evaluating LKBS. Besides considering evaluation
context and goals, they also propose evaluative criteria and guidelines alike. In this
framework, the quadrant criteria pertinent to the purposes of this paper are
herewith mentioned. The User Credibility quadrant refers to credibility and
acceptability of a system at the individual level. It comprises three main branches
associated with user satisfaction, utility (usefulness or tness for purpose) and
usability (ease of use). The usability branch is further decomposed into branches
associated with operability, understandability, learnability, accessibility,
exibility in use, and with other human factors and human computer interface issues.
The Veri cation and Validation criteria quadrant refer to knowledge base
validity, including knowledge representation and associated theories of jurisprudence,
inferencing, and the provision of explanations.
      </p>
      <p>
        The validation phase of legal modeling by domain legal experts { driven by
operational usability assessments { is also mentioned in the methodologies
referring to ontological expert knowledge evaluation. For example, the Methodology
for Modeling Legal Ontologies (MeLOn) [
        <xref ref-type="bibr" rid="ref14">14</xref>
        ] o ers evaluation parameters
consisting in completeness, correctness, coherence of the conceptualization phase
and artifact reusability. Usability concerns were considered in an experimental
validation of a legal ontology by legal experts, the Ontology of Professional
Judicial Knowledge (OPJK), described in [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ]. This model was validated in a two-step
process. First, the evaluators answered a questionnaire whereby they expressed
their opinion on their level of agreement towards the ontology
conceptualization and provided suggestions for the improvement thereof. Then an
experimental validation based on a usability questionnaire followed, the System Usability
Scale (SUS), tailored to evaluate the understandably and acceptance of the
contents of the ontology. This evaluation questionnaire could o er rapid feedback
and support towards the establishment of relevant agreement, shareability or
quality of content measurements in expert-based ontology evaluation. An
evaluation methodology based on Competency Questions (CQs) [
        <xref ref-type="bibr" rid="ref18">18</xref>
        ] was built to
evaluate the transformation of legal knowledge from a semi-formal form (Semantics
Of Business Vocabulary And Rules - Standard English (SBVR-SE)) [
        <xref ref-type="bibr" rid="ref13">13</xref>
        ] to a
more structured formal representation (OWL 2), and to enable cooperation
between legal expert and knowledge IT expert in charge of the modelling in logic
formalism. Ontology quality criteria were accounted for.
      </p>
      <p>Although the legal formal framework target of this work's analysis (i.e., the
DAPRECO Knowledge Base) refers and is strictly bound to a legally validated
ontology (i.e., the PrOnto) an argument for its legal validity cannot follow only
from the validity of the ontology of reference. It requires a more comprehensive
analysis and we believe that both qualitative evaluation methodologies and
certain criteria from the CCCF are required. Ontologies are in fact about concepts,
data, and entities and any validation strategy of them is inevitably about
assessing the legal qualities of those objects. Formal models for legal compliance,
such as the DAPRECO Knowledge Base, model also the logical and deontic
structure of a legal text, its temporal aspects and, as when the formalism allows
multiple con icting interpretations, as the DAPRECO Knowledge Base does, it
includes structural elements to allow defeasible reasoning. The validation
assessment should take these elements into account.</p>
      <p>Thus, the necessity of an integrated approach, which additionally should also
acknowledge an operational-usability assessment, since the legal validity of the
DAPRECO Knowledge Base logic formul have to be validated by people who
are not experts in logic.
3</p>
    </sec>
    <sec id="sec-3">
      <title>Background and Methods</title>
      <p>
        This work leverages on our previous work [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ] which discusses how to take the
formalization of GDPR provisions expressed in RIO logic [
        <xref ref-type="bibr" rid="ref20">20</xref>
        ] and how to extract
from them pieces of information that a legal expert will process of legal validity.
This, in fact, means to answer a questionnaire whose questions are meant to
provide feedback on speci c quality linked to the legal validity, such as
completeness, coherence, and conciseness (see later). We will refer to this synthetic
digest of an otherwise speci c logic formalism as human-readable representation
of a RIO formula.
      </p>
      <p>
        Empirical validation using tailored constructed questionnaire is a very
useful quantitative indicator of user acceptance [
        <xref ref-type="bibr" rid="ref26">26</xref>
        ]. In this case, where users are
lawyers, the questionnaire has been designed with the purpose of having legal
feedback on the quality of the legal interpretation in the RIO formul . The
questionnaire is build around six questions reported in Table 1.
      </p>
      <p>Does the deontic modality (obligation/permission/other) of the
forq1 mula coincide with the modality of the GDPR articles?
q2 Does the formula capture all the important legal concepts?
q3 Does the formula capture all the important legal relations?
q4 Is the interpretation given by the model correct?
q5 Is the interpretation complete?
q6 Is the interpretation to the point?</p>
      <p>They are tailored to check for the following legal validation qualities:
Accuracy (q1); Completeness (q2 q4); Consistency (q5); and Conciseness (q6).</p>
      <p>We now give two examples of human-readable representations accompanying
the questionnaire. Both examples will be referred later in this paper.</p>
      <sec id="sec-3-1">
        <title>Example 1. We refer to Article 7.1 of the GDPR, which reads:</title>
        <p>\Where processing is based on consent, the controller shall be able to
demonstrate that the data subject has consented to processing of his or
her personal data"</p>
        <p>
          Without entering into any detail on its modeling (the reader can refer to [
          <xref ref-type="bibr" rid="ref20">20</xref>
          ]
for it), RIO formula expressing this provision is the following:
( [ (RexistAtTime a1 t1) ^ (and a1 ep ehc eau edp) ^ (DataSubject w) ^
(PersonalData z w) ^ (Controller y z) ^ (Processor x) ^ (nominates0 edp y x) ^
(PersonalDataProcessing0 ep x z) ^ (Purpose epu) ^ (isBasedOn ep epu) ^
(Consent c) ^ (GiveConsent0 ehc w c) ^ (AuthorizedBy0 eau epu c) ]!
[ (RexistAtTime ea t1) ^ (AbleTo0 ea y ed) ^ (Demonstrate0 ed y ehc) ] ) 2 O
(1)
        </p>
        <p>
          Names like nominates and PersonalData are either chosen by the IT expert in
charge of the modelling in logic formalism or are taken from the PrOnto [
          <xref ref-type="bibr" rid="ref15 ref16 ref17">17,16,15</xref>
          ].
PrOnto is one of the three essential components along with the Akoma Ntoso
representation of the legal text and the formul in RIO logic. When connected
together the three components form the complete model of the GDPR. The
formula expresses an obligation, and that is what the O at the rightmost end
Equation (1) is supposed to mean. Equation (1) is not however what a user would
see. Stored to be machine-readable, the formula is written in its LegalRuleML
version. An excerpt of this version is given below.
        </p>
        <p>Listing 1. LegalRuleML representation of formula 1 (snippet).
&lt;r u l e m l : R u l e c l o s u r e=" u n i v e r s a l "&gt;
&lt; r u l e m l : i f&gt;
&lt;r u l e m l : E x i s t s&gt;
&lt;ruleml:And&gt;
&lt;ruleml:Atom&gt;
&lt;r u l e m l : R e l i r i =" rioOnto:RexistAtTime " /&gt;
&lt;r u l e m l : V a r k e y r e f=" : a 1 " /&gt;
&lt;r u l e m l : V a r key=" : t 1 "&gt;t1&lt;/ r u l e m l : V a r&gt;
&lt;/ ruleml:Atom&gt;
. . .
&lt;ruleml:Atom&gt;
&lt;r u l e m l : R e l i r i =" prOnto:DataSubject " /&gt;
&lt;r u l e m l : V a r k e y r e f=" :w " /&gt;
&lt;/ ruleml:Atom&gt;
. . .</p>
        <p>&lt;/ ruleml:And&gt;
&lt;/ r u l e m l : E x i s t s&gt;
&lt;/ r u l e m l : i f&gt;
&lt;r u l e m l : t h e n&gt;
&lt;r u l e m l : E x i s t s&gt;
&lt;ruleml:And&gt;
&lt;ruleml:Atom&gt;
&lt;r u l e m l : R e l i r i =" rioOnto:RexistAtTime " /&gt;
&lt;r u l e m l : V a r k e y r e f=" : e a " /&gt;
&lt;r u l e m l : V a r k e y r e f=" : t 1 " /&gt;
&lt;/ ruleml:Atom&gt;
. . .</p>
        <p>&lt;/ ruleml:And&gt;
&lt;/ r u l e m l : E x i s t s&gt;
&lt;/ r u l e m l : t h e n&gt;
&lt;/ r u l e m l : R u l e&gt;</p>
        <p>
          In [
          <xref ref-type="bibr" rid="ref1">1</xref>
          ], we described a parser that reads LegalRuleML and returns an itemized
structured representation of the formula whose intended meaning has not been
changed and is preserved in the translation. This version renders a cleaner version
without all those XML based tags which are quite hard to process by a human
reader. Applied to the LegalRuleML of (1), it results in the following text:
IF, in at least a situation,
{ At time :t1, the following situation exists:
(All of the following (:a1))
1. Processor (:x) does PersonalDataProcessing (:ep) of PersonalData (:z)
2. DataSubject (:w) performs a GiveConsent (:ehc) action on Consent (:c)
3. Purpose (:epu) is AuthorizedBy (:eau) Consent (:c)
4. Controller (:y) nominates (:edp) Processor (:x)
PersonalData (:z) is relating to DataSubject (:w)
The Controller (:y) is controlling PersonalData (:z)
        </p>
        <p>PersonalDataProcessing (:ep) isBasedOn Purpose (:epu)
THEN it must happen that, in at least a situation,
{ At time :t1, Controller (:y) is Obliged to AbleTo (:ea)</p>
        <p>Controller (:y) Demonstrate (:ed) GiveConsent (:ehc)</p>
        <p>The words capitalized and in bold are concepts from the PrOnto ontology.
The words in bold non-capitalized are relations introduced by the IT expert.
Although this format still requires some mental e ort to be read, it is at least
human-processable;</p>
        <p>The human-readable representation is built from the output of the parser
through a manual post-processing. That of Article 7.1 is shown in Table 2.</p>
        <p>There is a processing, which has a purpose authorized by a consent given by a
data subject, and that is what a processor, whom a controller controlling the
personal data nominates, does on personal data of the data of the data subject.</p>
        <p>Whenever there is a processing, which has a purpose authorized by a consent
given by a data subject, and that is what a processor, whom a controller
controlling the personal data nominates, does on personal data of the data of the
data subject then the controller is obliged to able to demonstrate that \data
subject gave consent".</p>
        <p>Example 2. We refer to Article 5.1(a) of the GDPR, which is worded as follows:
\Personal data shall be a) processed lawfully, fairly and in a transparent
manner in relation to the data subject (`lawfulness, fairness and
transparency');"</p>
        <p>The output of the re-interpretation of the RIO formula (here omitted for
reasons of space), transform the LegalRuleML as follows:</p>
        <p>IF, in at least a situation,
{ At time :t1, the following situation exists:
(All of the following (:a1))
1. The PersonalDataProcessing (:ep) is performed by Processor (:x) over the</p>
        <p>PersonalData (:z)
2. Controller (:y) nominates (:edp) Processor (:x)
PersonalData (:z) is relating to DataSubject (:w)</p>
        <p>The Controller (:y) is controlling PersonalData (:z)
THEN it must happen that, in at least a situation,
{ At, time t2, Controller (:y) is Obliged to
(All the following (:a2))
1. Controller (:y) Implement (:ei) Measure (:em)
2. The fact Measure (:em) is the cause of the fact lawfulness (:el)
3. The fact Measure (:em) is the cause of the fact fairness (:ef )
4. The fact Measure (:em) is the cause of the fact transparency (:et)
5. Controller (:y) Describe (:ed) Implement (:ei)
Thing (:t1) is greater than, or at least equal to, Thing (:t2)
PersonalDataProcessing (:ep) respects the principle of lawfulness (:el)
PersonalDataProcessing(:ep) respects the principle of fairness (:ef )
PersonalDataProcessing (:ep) respects the principle of transparency (:et)</p>
        <p>Task PersonalDataProcessing (:ep) is RelatedTo DataSubject (:w)</p>
      </sec>
      <sec id="sec-3-2">
        <title>The output of the hand-made processing is shown in Table 3.</title>
        <p>Ontological [[IPneRrseolantailodnaTtoa]]tshhea[lDlbatea[ Psurbocjeecsts]ed(`][ Llaawwffuulllny,esfsa]i,rl[yFaainrndesins] aantrda[nTsrpaanrsepnatrmenacnyn]'e)r;
Concepts
Other Onto- [Processor]; [Measure]; [Nominates]; [IsBasedOn]; [Implement]; [Describe]
logical
Concepts
Context
Overall
Meaning</p>
        <p>There is a processing done by a processor on personal data of the data subject,
and a controller, which is who controls the personal data; he nominates the
processor. The controller describes (how) he implements a measure.</p>
        <p>Whenever there is a processing done by a processor on personal data of the
data subject, and a controller, which is who controls the personal data and who
nominates the processor. Then before that moment must be that the controller
describes (how) he implements a measure that is what causes lawfulness, fairness
and transparency of the data processing related to the data subject.
4</p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>Validation and Discussion</title>
      <p>
        Can a legal validator reading the human-readable representation give useful
feedback to the modeller? Answering this question is the goal of this paper.
Rephrased, the goal is to show that the \Validation" phase of the methodology
presented in [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ] (see Figure 1) is e ective, i.e., helpful feedback can be collected
for the IT expert formalizing the GDPR with RIO logic.
      </p>
      <p>The starting point is the human-readable representation of Articles 5.1(a)
and 7.1 of the GDPR. The \Check" action (see Figure 1) has been implemented
by gathering a set of four validators, all jurists knowledgeable of data protection
law, and by asking them to answer questions q1 q6 in Table 1.</p>
      <p>Evaluators were told to compare the meaning of the formul , as expressed in
the human-readable representation of the RIO logic, with the legal interpretation
that them legal experts would give to the original articles in the GDPR.</p>
      <p>
        We also asked them a few questions meant to reveal how much
understandable for them is the human-readable format, before they start using it. General
understandability of the format has been discussed elsewhere [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ], but here the
assessment is meant as a trust measure over the expert's answers. However, all our
evaluators con rmed they have found the human-readable format
understandable. From those trusted answers, we therefore compile a few recommendations.
This is the \Generate Feedback" step in Figure 1.
      </p>
      <p>Questions q1 q6 (see Table 1) are yes/no questions, but in the questionnaire
we additionally invited our checkers to motivate their answers and to pinpoint
further whatever observation they valued meaningful. We collected eight
documents with such written answers and comments which we reviewed and
summarized. The following table resumes the ndings, wherein we report the comments
whenever the answer to the question was `no', indicating that someone found
some pertinent issue.</p>
      <p>For instance, all experts easily understood and con rmed the deontic
modality and agreed on the formulas be capturing all the legal concepts and relations
(see Table 5). But is from the analysis conferred to the provided comments that
we are able o er a broader spectrum, for they refer to the above surveyed criteria
and also to other (non-surveyed) related criteria. Comments { in Completeness
like \it was complex to capture the legal concepts within the structure of the
formula"; comments in Consistency like \It refers to the implementation and
description of a measure that it is hard to understand; \It is redundant and
restates concepts already present at previous articles", and comments in
Conciseness like \'Obliged to be able to' sounds weirds" { clearly indicate uneasiness
about the way in which the formula have been structured; such comments may
lead to a better formalization, for instance, stating certain contextual facts as a
common premise valid for all the GDPR's articles without repeating them each
time in each article.</p>
      <p>One evaluator, in particular, has mentioned \Interchanged roles for the
controller and the processor" in Consistency. Even if that is stated in the Context of
the human-readable table, the evaluator was probably induced in error/confused
by the excess of information provided. Further analysis is of course required.
Extracting from the non-structured comments valid input for the IT expert has to
be left as future work, as we comment in the following section.
5</p>
    </sec>
    <sec id="sec-5">
      <title>Conclusions and future work</title>
      <p>This paper leverages a methodology that advocates an interdisciplinary
validation of a representation of the GDPR articles in a logic formalism (i.e., RIO
logic) to pursue quality, accountability, and transparency within. One
important output of the methodology is the production of feedback derived from the
involvement of legal experts, while assessing the quality of the legal
interpretation that IT experts may instill in the formalization of the GDPR. This work
has gathered evidence that such step is feasible. As a proof-of-concept, a small
number of legal experts has been asked to answer six questions with the
purpose of collecting comments about how two logic formul , modelling Articles
5.1a and 7.1 of the GDPR, are complete, accurate, concise, and consistent in
reecting the legal meaning of the articles. Several comments have been collected.
Although a thorough analysis thereof requires more time { an involvement of a
larger group of expert checkers is also advisable{ we were able to identify a few
issues of relevance using which the IT expert can review the formalization work.</p>
      <p>Several challenges await us in the near future. We need to improve scalability
in producing a human-readable representation of the RIO formul : it is currently
done manually, starting from the pre-processed version. This is already more
readable than the original LegalRuleML version and give us con dence that the
work to produce a natural language analysis break-up table can be automatized.
This step done, a forth bringing process will consist in streamlining the validation
of the RIO formalization of the GDPR as a whole. This likely requires to set up
an application where the work of the IT expert can be suitably translated in to
the human-readable format and o ered for on-line checking to a group of legal
testers, which may also vary, providing feedback that the IT expert can take
into consideration until a good quality of legal interpretation is assessed for the
formul .</p>
      <p>
        Concomitantly, there is a need to de ne together with the legal experts a more
complete set of qualities and possibly a few metrics, which we can quantify and
de ne criteria on the legal quality of the formalization. In Section 2 we pointed
out possible metrics, and in this paper we have assessed a few (completeness,
consistency, conciseness in Section 4), but a wide and systematic investigation
of the state-of-the-art in this topic has not been done yet. The quadrant criteria
presented in [
        <xref ref-type="bibr" rid="ref10">10</xref>
        ] also merits attention. This may lead to a revision of the current
human-readable model.
      </p>
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