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Richards Robert

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Semantic Enhancement of Legal Information… Are We Up for the Challenge? [Revised Repost]

Cross-language legal information retrieval, information retrieval, knowledge management, Legal knowledge representation, Legal ontologies, Legal semantic web, Linked Data, Linked Data and law, Multilingual legal information retrieval, Semantic Web and law 1 Response »
Jan 182011

WorldLII[Editor’s Note: We are republishing here, with some corrections, a post by Dr. Núria Casellas that appeared earlier on VoxPopuLII.]

The organization and formalization of legal information for computer processing in order to support decision-making or enhance information search, retrieval and knowledge management is not recent, and neither is the need to represent legal knowledge in a machine-readable form. Nevertheless, since the first ideas of computerization of the law in the late 1940s, the appearance of the first legal information systems in the 1950s, and the first legal expert systems in the 1970s, claims, such as Hafner’s, that “searching a large database is an important and time-consuming part of legal work,” which drove the development of legal information systems during the 80s, have not yet been left behind.

Similar claims may be found nowadays as, on the one hand, the amount of available unstructured (or poorly structured) legal information and documents made available by governments, free access initiatives, blawgs, and portals on the Web will probably keep growing as the Web expands. And, on the other, the increasing quantity of legal data managed by legal publishing companies, law firms, and government agencies, together with the high quality requirements applicable to legal information/knowledge search, discovery, and management (e.g., access and privacy issues, copyright, etc.) have renewed the need to develop and implement better content management tools and methods.

Information overload, however important, is not the only concern for the future of legal knowledge management; other and growing demands are increasing the complexity of the requirements that legal information management systems and, in consequence, legal knowledge representation must face in the future. Multilingual search and retrieval of legal information to enable, for example, integrated search between the legislation of several European countries; enhanced laypersons’ understanding of and access to e-government and e-administration sites or online dispute resolution capabilities (e.g., BATNA determination); the regulatory basis and capabilities of electronic institutions or normative and multi-agent systems (MAS); and multimedia, privacy or digital rights management systems, are just some examples of these demands.

How may we enable legal information interoperability? How may we foster legal knowledge usability and reuse between information and knowledge systems? How may we go beyond the mere linking of legal documents or the use of keywords or Boolean operators for legal information search? How may we formalize legal concepts and procedures in a machine-understandable form?

In short, how may we handle the complexity of legal knowledge to enhance legal information search and retrieval or knowledge management, taking into account the structure and dynamic character of legal knowledge, its relation with common sense concepts, the distinct theoretical perspectives, the flavor and influence of legal practice in its evolution, and jurisdictional and linguistic differences?

These are challenging tasks, for which different solutions and lines of research have been proposed. Here, I would like to draw your attention to the development of semantic solutions and applications and the construction of formal structures for representing legal concepts in order to make human-machine communication and understanding possible.

Semantic metadata

For example, in the search and retrieval area, we still perform nowadays most legal searches in online or application databases using keywords (that we believe to be contained in the document that we are searching for), maybe together with a combination of Boolean operators, or supported with a set of predefined categories (metadata regarding, for example, date, type of court, etc.), a list of pre-established topics, thesauri (e.g., EuroVoc), or a synonym-enhanced search.

These searches rely mainly on syntactic matching, and — with the exception of searches enhanced with categories, synonyms, or thesauri — they will return only documents that contain the exact term searched for. To perform more complex searches, to go beyond the term, we require the search engine to understand the semantic level of legal documents; a shared understanding of the domain of knowledge becomes necessary.

Although the quest for the representation of legal concepts is not new, these efforts have recently been driven by the success of the World Wide Web (WWW) and, especially, by the later development of the Semantic Web. Sir Tim Berners-Lee described it as an extension of the Web “in which information is given well-defined meaning, better enabling computers and people to work in cooperation.”

From Web 2.0 to Web 3.0

Thus, the Semantic Web is envisaged as an extension of the current Web, which now comprises collaborative tools and social networks (the Social Web or Web 2.0). The Semantic Web is sometimes also referred to as Web 3.0, although there is no widespread agreement on this matter, as different visions exist regarding the enhancement and evolution of the current Web.

These efforts also include the Web of Data (or Linked Data), which relies on the existence of standard formats (URIs, HTTP and RDF) to allow the access and query of interrelated datasets, which may be granted through a SPARQL endpoint (e.g., Govtrack.us, US census data, etc.). Sharing and connecting data on the Web in compliance with the Linked Data principles enables the exploitation of content from different Web data sources with the development of search, browse, and other mashup applications. (See the Linking Open Data cloud diagram by Cyganiak and Jentzsch below.) [Editor’s Note: Legislation.gov.uk also applies Linked Data principles to legal information, as John Sheridan explains in his recent post.]

LinkedData

Thus, to allow semantics to be added to the current Web, new languages and tools (ontologies) were needed, as the development of the Semantic Web is based on the formal representation of meaning in order to share with computers the flexibility, intuition, and capabilities of the conceptual structures of human natural languages. In the subfield of computer science and information science known as Knowledge Representation, the term “ontology” refers to a consensual and reusable vocabulary of identified concepts and their relationships regarding some phenomena of the world, which is made explicit in a machine-readable language. Ontologies may be regarded as advanced taxonomical structures, Semantic Web Stackwhere concepts are formalized as classes and defined with axioms, enriched with the description of attributes or constraints, and properties.

The task of developing interoperable technologies (ontology languages, guidelines, software, and tools) has been taken up by the World Wide Web Consortium (W3C). These technologies were arranged in the Semantic Web Stack according to increasing levels of complexity (like a layer cake). In this stack, higher layers depend on lower layers (and the latter are inherited from the original Web). These languages include XML (eXtensible Markup Language), a superset of HTML usually used to add structure to documents, and the so-called ontology languages: RDF/RDFS (Resource Description Framework/Schema), OWL, and OWL2 (Ontology Web Language). While the RDF language offers simple descriptive information about the resources on the Web, encoded in sets of triples of subject (a resource), predicate (a property or relation), and object (a resource or a value), RDFS allows the description of sets. OWL offers an even more expressive language to define structured ontologies (e.g. class disjointess, union or equivalence, etc.

Moreover, a specification to support the conversion of existing thesauri, taxonomies or subject headings into RDF triples has recently been published: the SKOS, Simple Knowledge Organization System standard. These specifications may be exploited in Linked Data efforts, such as the New York Times vocabularies. Also, EuroVoc, the multilingual thesaurus for activities of the EU is, for example, now available in this format.

Although there are different views in the literature regarding the scope of the definition or main characteristics of ontologies, the use of ontologies is seen as the key to implementing semantics for human-machine communication. Many ontologies have been built for different purposes and knowledge domains, for example:

  • OpenCyc: an open source version of the Cyc general ontology;
  • SUMO: the Suggested Upper Merged Ontology;
  • the upper ontologies PROTON (PROTo Ontology) and DOLCE (Descriptive Ontology for Linguistic and Cognitive Engineering);
  • the FRBRoo model (which represents bibliographic information);
  • the RDF representation of Dublin Core;
  • the Gene Ontology;
  • the FOAF (Friend of a Friend) ontology.

Although most domains are of interest for ontology modeling, the legal domain offers a perfect area for conceptual modeling and knowledge representation to be used in different types of intelligent applications and legal reasoning systems, not only due to its complexity as a knowledge intensive domain, but also because of the large amount of data that it generates. The use of semantically-enabled technologies for legal knowledge management could provide legal professionals and citizens with better access to legal information; enhance the storage, search, and retrieval of legal information; make possible advanced knowledge management systems; enable human-computer interaction; and even satisfy some hopes respecting automated reasoning and argumentation.

Regarding the incorporation of legal knowledge into the Web or into IT applications, or the more complex realization of the Legal Semantic Web, several directions have been taken, such as the development of XML standards for legal documentation and drafting (including Akoma Ntoso, LexML, CEN Metalex, and Norme in Rete), and the construction of legal ontologies.

Ontologizing legal knowledge

During the last decade, research on the use of legal ontologies as a technique to represent legal knowledge has increased and, as a consequence, a very interesting debate about their capacity to represent legal concepts and their relation to the different existing legal theories has arisen. It has even been suggested that ontologies could be the “missing link” between legal theory and Artificial Intelligence.

The literature suggests that legal ontologies may be distinguished by the levels of abstraction of the ideas they represent, the key distinction being between core and domain levels. Legal core ontologies model general concepts which are believed to be central for the understanding of law and may be used in all legal domains. In the past, ontologies of this type were mainly built upon insights provided by legal theory and largely influenced by normativism and legal positivism, especially by the works of Hart and Kelsen. Thus, initial legal ontology development efforts in Europe were influenced by hopes and trends in research on legal expert systems based on syllogistic approaches to legal interpretation.

More recent contributions at that level include the LKIF-Core Ontology, the LRI-Core Ontology, the DOLCE+CLO (Core Legal Ontology), and the Ontology of Fundamental Legal Concepts.Blue Scene Such ontologies usually include references to the concepts of Norm, Legal Act, and Legal Person, and may contain the formalization of deontic operators (e.g., Prohibition, Obligation, and Permission).

Domain ontologies, on the other hand, are directed towards the representation of conceptual knowledge regarding specific areas of the law or domains of practice, and are built with particular applications in mind, especially those that enable communication (shared vocabularies), or enhance indexing, search, and retrieval of legal information. Currently, most legal ontologies being developed are domain-specific ontologies, and some areas of legal knowledge have been heavily targeted, notably the representation of intellectual property rights respecting digital rights management (IPROnto Ontology, the Copyright Ontology, the Ontology of Licences, and the ALIS IP Ontology), and consumer-related legal issues (the Customer Complaint Ontology (or CContology), and the Consumer Protection Ontology). Many other well-documented ontologies have also been developed for purposes of the detection of financial fraud and other crimes; the representation of alternative dispute resolution methods, privacy compliance, patents, cases (e.g., Legal Case OWL Ontology), judicial proceedings, legal systems, and argumentation frameworks; and the multilingual retrieval of European law, among others. (See, for example, the proceedings of the JURIX and ICAIL conferences for further references.)

A socio-legal approach to legal ontology development

Thus, there are many approaches to the development of legal ontologies. Nevertheless, in the current legal ontology literature there are few explicit accounts or insights into the methods researchers use to elicit legal knowledge, and the accounts that are available reflect a lack of consensus as to the most appropriate methodology. For example, some accounts focus solely on the use of text mining techniques towards ontology learning from legal texts; while others concentrate on the analysis of legal theories and related materials to extract and formalize legal concepts. Moreover, legal ontology researchers disagree about the role that legal experts should play in ontology development and validation.

Orange SceneIn this regard, at the Institute of Law and Technology, we are developing a socio-legal approach to the construction of legal conceptual models. This approach stems from our collaboration with firms, government agencies, and nonprofit organizations (and their experts, clients, and other users) for the gathering of either explicit or tacit knowledge according to their needs. This empirically-based methodology may require the modeling of legal knowledge in practice (or professional legal knowledge, PLK), and the acquisition of knowledge through ethnographic and other social science research methods, together with the extraction (and merging) of concepts from a range of different sources (acts, regulations, case law, protocols, technical reports, etc.) and their validation by both legal experts and users.

For example, the Ontology of Professional Judicial Knowledge (OPJK) was developed in collaboration with the Spanish School of the Judicary to enhance search and retrieval capabilities of a Web-based frequentl- asked-question system (IURISERVICE) containing a repository of practical knowledge for Spanish judges in their first appointment. The knowledge was elicited from an ethnographic survey in Spanish First Instance Courts. On the other hand, the Neurona Ontologies, for a data protection compliance application, are based on the knowledge of legal experts and the requirements of enterprise asset management, together with the analysis of privacy and data protection regulations and technical risk management standards.

This approach tries to take into account many of the criticisms that developers of legal knowledge-based systems (LKBS) received during the 1980s and the beginning of the 1990s, including, primarily, the lack of legal knowledge or legal domain understanding of most LKBS development teams at the time. These criticisms were rooted in the widespread use of legal sources (statutes, case law, etc.) directly as the knowledge for the knowledge base, instead of including in the knowledge base the “expert” knowledge of lawyers or law-related professionals.

Further, in order to represent knowledge in practice (PLK), legal ontology engineering could benefit from the use of social science research methods for knowledge elicitation, institutional/organizational analysis (institutional ethnography), as well as close collaboration with legal practitioners, users, experts, and other stakeholders, in order to discover the relevant conceptual models that ought to be represented in the ontologies. Moreover, I understand the participation of these stakeholders in ontology evaluation and validation to be crucial to ensuring consensus about, and the usability of, a given legal ontology.

Challenges and drawbacks

Although the use of ontologies and the implementation of the Semantic Web vision may offer great advantages to information and knowledge management, there are great challenges and problems to be overcome.

First, the problems related to knowledge acquisition techniques and bottlenecks in software engineering are inherent in ontology engineering, and ontology development is quite a time-consuming and complex task. Second, as ontologies are directed mainly towards enabling some communication on the basis of shared conceptualizations, how are we to determine the sharedness of a concept? And how are context-dependencies or (cultural) diversities to be represented? Furthermore, how can we evaluate the content of ontologies?

Collaborative Current research is focused on overcoming these problems through the establishment of gold standards in concept extraction and ontology learning from texts, and the idea of collaborative development of legal ontologies, although these techniques might be unsuitable for the development of certain types of ontologies. Also, evaluation (validation, verification, and assessment) and quality measurement of ontologies are currently an important topic of research, especially ontology assessment and comparison for reuse purposes.

Regarding ontology reuse, the general belief is that the more abstract (or core) an ontology is, the less it owes to any particular domain and, therefore, the more reusable it becomes across domains and applications. This generates a usability-reusability trade-off that is often difficult to resolve.

Finally, once created, how are these ontologies to evolve? How are ontologies to be maintained and new concepts added to them?

Over and above these issues, in the legal domain there are taking place more particularized discussions:  for example, the discussion of the advantages and drawbacks of adopting an empirically based perspective (bottom-up), and the complexity of establishing clear connections with legal dogmatics or general legal theory approaches (top-down). To what extent are these two different perspectives on legal ontology development incompatible? How might they complement each other? What is their relationship with text-based approaches to legal ontology modeling?

I would suggest that empirically based, socio-legal methods of ontology construction constitute a bottom-up approach that enhances the usability of ontologies, while the general legal theory-based approach to ontology engineering fosters the reusability of ontologies across multiple domains.

The scholarly discussion of legal ontology development also embraces more fundamental issues, among them the capabilities of ontology languages for the representation of legal concepts, the possibilities of incorporating a legal flavor into OWL, and the implications of combining ontology languages with the formalization of rules.

Finally, the potential value to legal ontology of other approaches, areas of expertise, and domains of knowledge construction ought to be explored, for example: pragmatics and sociology of law methodologies, experiences in biomedical ontology engineering, formal ontology approaches, salamander.jpgand the relationships between legal ontology and legal epistemology, legal knowledge and common sense or world knowledge, expert and layperson’s knowledge, legal information and Linked Data possibilities, and legal dogmatics and political science (e.g., in e-Government ontologies).

As you may see, the challenges faced by legal ontology engineering are great, and the limitations of legal ontologies are substantial. Nevertheless, the potential of legal ontologies is immense. I believe that law-related professionals and legal experts have a central role to play in the successful development of legal ontologies and legal semantic applications.

[Editor’s Note: For many of us, the technical aspects of ontologies and the Semantic Web are unfamiliar. Yet these technologies are increasingly being incorporated into the legal information systems that we use everyday, so it’s in our interest to learn more about them. For those of us who would like a user-friendly introduction to ontologies and the Semantic Web, here are some suggestions:

Dr. Núria Casellas Dr. Núria Casellas is a visiting researcher at the Legal Information Institute at Cornell University. She is a researcher at the Institute of Law and Technology and an assistant professor at the UAB Law School (on leave). She has participated in several national and European-funded research projects regarding legal ontologies and legal knowledge management: these concern the acquisition of knowledge in judicial settings (IURISERVICE), modeling privacy compliance regulations (NEURONA), drafting legislation (DALOS), and the Legal Case Study of the Semantically Enabled Knowledge Technologies (SEKT VI Framework project), among others. Co-editor of the IDT Series, she holds a Law Degree from the Universitat Autònoma de Barcelona, a Master’s Degree in Health Care Ethics and Law from the University of Manchester, and a PhD (“Modelling Legal Knowledge through Ontologies. OPJK: the Ontology of Professional Judicial Knowledge”).

VoxPopuLII is edited by Judith Pratt. Editor in Chief is Robert Richards.

Posted by Richards Robert at 11:31 pm Tagged with:

Weaving the Legal Semantic Web with Natural Language Processing

Annotation of legal texts, information retrieval, Legal knowledge representation, Legal semantic web, Legal text mining, Legal text processing, Legal XML, natural language processing, Semantic annotation of legal texts, Semantic Web and law 4 Responses »
May 172010

CornucopiaThe World Wide Web is a virtual cornucopia of legal information bearing on all manner of topics and in a spectrum of formats, much of it textual. However, to make use of this storehouse of textual information, it must be annotated and structured in such a way as to be meaningful to people and processable by computers. One of the visions of the Semantic Web has been to enrich information on the Web with annotation and structure. Yet, given that text is in a natural language (e.g., English, German, Japanese, etc.), which people can understand but machines cannot, some automated processing of the text itself is needed before further processing can be applied. In this article, we discuss one approach to legal information on the World Wide Web, the Semantic Web, and Natural Language Processing (NLP). Each of these are large, complex, and heterogeneous topics of research; in this short post, we can only hope to touch on a fragment and that heavily biased to our interests and knowledge. Other important approaches are mentioned at the end of the post. We give small working examples of legal textual input, the Semantic Web output, and how NLP can be used to process the input into the output.

Legal Information on the Web

For clients, legal professionals, and public administrators, the Web provides an unprecedented opportunity to search for, find, and reason with legal information such as case law, legislation, legal opinions, journal articles, and material relevant to discovery in a court procedure. With a search tool such as Google or indexed searches made available by Lexis-Nexis, Westlaw, or the World Legal Information Institute, the legal researcher can input key words into a search and get in return a (usually long) list of documents which contain, or are indexed by, those key words.

As useful as such searches are, they are also highly limited to the particular words or indexation provided, for the legal researcher must still manually examine the documents to find the substantive information. Moreover, current legal search mechanisms do not support more meaningful searches such as for properties or relationships, where, for example, a legal researcher searches for cases in which a company has the property of being in the role of plaintiff or where a lawyer is in the relationship of representing a client. Nor, by the same token, can searches be made with respect to more general (or more specific) concepts, such as “all cases in which a company has any role,” some particular fact pattern, legislation bearing on related topics, or decisions on topics related to a legal subject.

Binary MysteryThe underlying problem is that legal textual information is expressed in natural language. What literate people read as meaningful words and sentences appear to a computer as just strings of ones and zeros. Only by imposing some structure on the binary code is it converted to textual characters as we know them. Yet, there is no similar widespread system for converting the characters into higher levels of structure which correlate to our understanding of meaning. While a search can be made for the string plaintiff, there are no (widely available) searches for a string that represents an individual who bears the role of plaintiff. To make language on the Web more meaningful and structured, additional content must be added to the source material, which is where the Semantic Web and Natural Language Processing come into play.

Semantic Web

The Semantic Web is a complex of design principles and technologies which are intended to make information on the Web more meaningful and usable to people.Semantic Web Stack We focus on only a small portion of this structure, namely the syntactic XML (eXtensible Markup Language) level, where elements are annotated so as to indicate linguistically relevant information and structure. (Click here for more on these points.) While the XML level may be construed as a ‘lower’ level in the Semantic Web “stack” — i.e., the layers of interrelated technologies that make up the Semantic Web — the XML level is nonetheless crucial to providing information to higher levels where ontologies (and click here for more on this) and logic play a role. So as to be clear about the relation between the Semantic Web and NLP, we briefly review aspects of XML by example, and furnish motivations as we go.

Suppose one looks up a case where Harris Hill is the plaintiff and Jane Smith is the attorney for Harris Hill. In a document related to this case, we would see text such as the following portions:

Harris Hill, plaintiff.
Jane Smith, attorney for the plaintiff.

While it is relatively straightforward to structure the binary string into characters, adding further information is more difficult. Consider what we know about this small fragment: Harris and Jane are (very likely) first names, Hill and Smith are last names, Harris Hill and Jane Smith are full names of people, plaintiff and attorney are roles in a legal case, Harris Hill has the role of plaintiff, attorney for is a relationship between two entities, and Jane Smith is in the attorney for relationship to Harris Hill. It would be useful to encode this information into a standardised machine-readable and processable form.

XML helps to encode the information by specifying requirements for tags that can be used to annotate the text. It is a highly expressive language, allowing one to define tags that suit one’s purposes so long as the specification requirements are met. One requirement is that each tag has a beginning and an ending; the material in between is the data that is being tagged. For example, suppose tags such as the following, where … indicates the data:


<legalcase>...</legalcase>,
<firstname>...</firstname>,
<lastname>...</lastname>,
<fullname>...</fullname>,
<plaintiff>...</plaintiff>,
<attorney>...</attorney>, 
<legalrelationship>...</legalrelationship>

Another requirement is that the tags have a tree structure, where each pair of tags in the document is included in another pair of tags and there is no crossing over:


<fullname><firstname>...</firstname>, 
<lastname>...</lastname></fullname>

is acceptable, but


<fullname><firstname>...<lastname>
</firstname> ...</lastname></fullname>

is unacceptable. Finally, XML tags can be organised into schemas to structure the tags.

With these points in mind, we could represent our fragment as:


<legalcase>
  <legalrelationship>
    <plaintiff>
      <fullname><firstname>Harris</firstname>,
           <lastname>Hill</lastname></fullname>
    </plaintiff>,
    <attorney>
      <fullname><firstname>Jane</firstname>,
           <lastname>Smith</lastname></fullname>
    </attorney>
  </legalrelationship
</legalcase>

We have added structured information — the tags — to the original text. While this is more difficult for us to read, it is very easy for a machine to read and process. In addition, the tagged text contains the content of the information, which can be presented in a range of alternative ways and formats using a transformation language such as XSLT (click here for more on this point) so that we have an easier-to-read format.

Why bother to include all this additional information in a legal text? Because these additions allow us to query the source text and submit the information to further processing such as inference. Given a query language, we could submit to the machine the query Who is the attorney in the case? and the answer would be Jane Smith. Given a rule language — such as RuleML or Semantic Web Rule Language (SWRL) — which has a rule such as If someone is an attorney for a client then that client has a privileged relationship with the attorney, it might follow from this rule that the attorney could not divulge the client’s secrets. Applying such a rule to our sample, we could infer that Jane Smith cannot divulge Harris Hill’s secrets.

Tower of BabelThough it may seem here like too much technology for such a small and obvious task, it is essential where we scale up our queries and inferences on large corpora of legal texts — hundreds of thousands if not millions of documents — which comprise vast storehouses of unstructured, yet meaningful data. Were all legal cases uniformly annotated, we could, in principle, find out every attorney for every plaintiff for every legal case. Where our tagging structure is very rich, our queries and inferences could also be very rich and detailed. Perhaps a more familiar way to view documents annotated with XML is as a database to which further processes can be applied over the Web.

Natural Language Processing

As we have presented it, we have an input, the corpus of texts, and an output, texts annotated with XML tags. The objective is to support a range of processes such as querying and inference. However, getting from a corpus of textual information to annotated output is a demanding task, generically referred to as the knowledge acquisition bottleneck. Not only is the task demanding on resources (time, money, manpower); it is also highly knowledge intensive since whoever is doing the annotation must know what to look for, and it is important that all of the annotators annotate the text in the same way (inter-annotator agreement) to support the processes. Thus, automation is central.

Yet processing language to support such richly annotated documents confronts a spectrum of difficult issues. Among them, natural language supports (1) implicit or presupposed information, (2) multiple forms with the same meaning, (3) the same form with different contextually dependent meanings, and (4) dispersed meanings. (Similar points can be made for sentences or other linguistic elements.) Here are examples of these four issues:

(1) “When did you stop taking drugs?” (presupposes that the person being questioned took drugs at sometime in the past);
(2) Jane Smith, Jane R. Smith, Smith, Attorney Smith… (different ways to refer to the same person);
(3) The individual referred to by the name “Jane Smith” in one case decision may not be the individual referred to by the name “Jane Smith” in another case decision;
(4) Jane Smith represented Jones Inc. She works for Dewey, Cheetum, and Howe. To contact her, write to j.smith@dch.com .

When we search for information, a range of linguistic structures or relationships may be relevant to our query, such as:

People grasp relationships between words and phrases, such that Bill exercises daily contrasts with the meaning of Bill is a couch potato, or that if it is true that Bill used a knife to kill Phil, then Bill killed Phil. Finally, meaning tends to be sparse; that is, there are a few words and patterns that occur very regularly, while most words or patterns occur relatively rarely in the corpus.

Natural language processing (NLP) takes on this highly complex and daunting problem as an engineering problem, decomposing large problems into smaller problems and subdomains until it gets to those which it can begin to address. Having found a solution to smaller problems, NLP can then address other problems or larger scope problems. Some of the subtopics in NLP are:

  • Generation – converting information in a database into natural language.
  • Understanding – converting natural language into a machine-readable form.
  • Information Retrieval – gathering documents which contain key words or phrases. This is essentially what is done by Google.
  • Text Summarization – summarizing (in a paragraph) the main meaning of a text or corpus.
  • Question Answering – making queries and giving answers to them, in natural language, with respect to some corpus of texts.
  • Information Extraction — identifying, annotating, and extracting information from documents for reuse, representation, or reasoning.

In this article, we are primarily (here) interested in information extraction.

NLP Approaches: Knowledge Light v. Knowledge Heavy

There are a range of techniques that one can apply to analyse the linguistic data obtained from legal texts; each of these techniques has strengths and weaknesses with respect to different problems. Statistical and machine-learning techniques are considered “knowledge light.” With statistical approaches, the processing presumes very little knowledge by the system (or analyst). Rather, algorithms are applied that compare and contrast large bodies of textual data, and identify regularities and similarities. Such algorithms encounter problems with sparse data or patterns that are widely dispersed across the text. (See Turney and Pantel (2010) for an overview of this area.) Machine learning approaches apply learning algorithms to annotated material to extend results to unannotated material, thus introducing more knowledge into the processing pipeline. However, the results are somewhat of a black box in that we cannot really know the rules that are learned and use them further.

With a “knowledge-heavy” approach, we know, in a sense, what we are looking for, and make this knowledge explicit in lists and rules for processing. Yet, this is labour- and knowledge-intensive. In the legal domain it is crucial to have humanly understandable explanations and justifications for the analysis of a text, which to our thinking warrants a knowledge-heavy approach.

One open source text-mining package, General Architecture for Text Engineering (GATE), consists of multiple components in a cascade or pipeline, each component automatically processing some aspect of the text, and then feeding into the next process. The underlying strategy in all the components is to find a pattern (from either a list or a previous process) which matches a rule, and then to apply the rule which annotates the text. Each component performs a particular process on the text, such as:

  • Sentence segmentation – dividing text into sentences.
  • Tokenisation – words identified by spaces between them.
  • Part-of-speech tagging – noun, verb, adjective, etc., determined by look-up and relationships among words.
  • Shallow syntactic parsing/chunking – dividing the text by noun phrase, verb phrase, subordinate clause, etc.
  • Named entity recognition – the entities in the text such as organisations, people, and places.
  • Dependency analysis – subordinate clauses, pronominal anaphora [i.e., identifying what a pronoun refers to], etc.

The system can also be used to annotate more specifically to elements of interest. In one study, we annotated legal cases from a case base (a corpus of cases) in order to identify a range of particular pieces of information that would be relevant to legal professionals such as:

  • Case citation.
  • Names of parties.
  • Roles of parties, meaning plaintiff or defendant.
  • Type of court.
  • Names of judges.
  • Names of attorneys.
  • Roles of attorneys, meaning the side they represent.
  • Final decision.
  • Cases cited.
  • Nature of the case, meaning using keywords to classify the case in terms of subject (e.g., criminal assault, intellectual property, etc.)

Applying our lists and rules to a corpus of legal cases, a sample output is as follows, where the coloured highlights are annotated as per the key on the right; the colours are a visualisation of the sorts of tags discussed above (to see a larger version of the image, right click on the image, then click on “View Image” or a similar phrase; when finished viewing the image, use the browser’s back button to return to the text):

Annotation of a Criminal Case

The approach is very flexible and appears in similar systems. (See, for example, de Maat and Winkels, Automatic Classification of Sentences in Dutch Laws (2008).) While it is labour intensive to develop and maintain such list and rule systems, with a collaborative, Web-based approach, it may be feasible to construct rich systems to annotate large domains.

Conclusion

In this post, we have given a very brief overview of how the Semantic Web and Natural Language Processing (NLP) apply to legal textual information to support annotation which then enables querying and inference. Of course, this is but one take on a much larger domain. In our view, it holds great promise in making legal information more transparent and available to more legal professionals. Aside from GATE, some other resources on text analytics and NLP are textbooks and lecture notes (see, e.g., Wilcock), as well as workshops (such as SPLeT and LOAIT). While applications of Natural Language Processing to legal materials are largely lab studies, the use of NLP in conjunction with Semantic Web technology to annotate legal texts is a fast-developing, results-oriented area which targets meaningful applications for legal professionals. It is well worth watching.

Adam WynerDr. Adam Zachary Wyner is a Research Fellow at the University of Leeds, Institute of Communication Studies, Centre for Digital Citizenship. He currently works on the EU-funded project IMPACT: Integrated Method for Policy Making Using Argument Modelling and Computer Assisted Text Analysis. Dr. Wyner has a Ph.D. in Linguistics (Cornell, 1994) and a Ph.D. in Computer Science (King’s College London, 2008). His computer science Ph.D. dissertation is entitled Violations and Fulfillments in the Formal Representation of Contracts. He has published in the syntax and semantics of adverbs, deontic logic, legal ontologies, and argumentation theory with special reference to law. He is workshop co-chair of SPLeT 2010: Workshop on Semantic Processing of Legal Texts, to be held 23 May 2010 in Malta. He writes about his research at his blog, Language, Logic, Law, Software.

VoxPopuLII is edited by Judith Pratt. Editor in chief is Robert Richards.

Posted by Richards Robert at 2:27 pm Tagged with: , ,

A Law Librarian Looks at Legal Informatics Scholarship

Digital law libraries, Law librarians and legal informatics, Legal informatics 2 Responses »
Jun 152009

Recently I, like many law librarians (including Dean Richard Danner, James Donovan, and the panelists at the University of South Carolina School of Law’s colloquium on “The Law Librarian’s Role in the Scholarly Enterprise” [scroll down & click on “Part 9: Roundtable”]), began to devote more thought to disintermediation in legal information services.  One way that law librarians can adapt to disintermediation is by learning more about the study of legal information systems, that is, legal informatics.  When I began looking closely at legal informatics scholarship last fall, I was dismayed at not being able to locate any single resource that aggregated all of the major scholarly information resources in the field.   As a result, I decided to build one; it’s called Legal Information Systems & Legal Informatics Resources. To provide current information, the site has an accompanying blog , the Legal Informatics Blog, and a Twitter feed.   Building these sites has allowed me to cast a novice’s eye on the field of legal informatics.

Eye

Here is what I’ve glimpsed in the past few months:

I. Surveying the Sources

My exploration of legal informatics has focused initially on information resources. A relatively circumscribed set of scholarly journals, other article sources, preprint services, indexing & abstracting services, blogs, and listservs regularly report research results in legal informatics. A small set of subject headings will retrieve most monographs and dissertations in the field. Accordingly, aggregating access to these resources has been relatively easy, and automating discovery and delivery of many of these sources seems feasible sooner rather than later.

Conferences are trickier.   The number of conferences at which legal informatics issues are addressed is substantial, for several reasons: a large number of researchers from industry as well as academia (see, e.g., the lists of individuals compiled by Dr. Adam Wyner and the organizers of the DEON deontic logic conferences, and this list of departments & institutes), energetically engaged in applied as well as theoretical research, are producing a sizeable output; many of those researchers work in multiple fields; and the pace of technological change is accelerating the research and communication processes.  Several Websites, such as those of the International Association for Artificial Intelligence and Law (IAAIL) and the DEON deontic logic conferences, monitor these meetings, however. Access to proceedings is available from several sources, including ACM’s Portal service, the other major information science indexing services, OCLC WorldCat, and the Legal Information Systems site. As a result, access to most legal informatics conference information and proceedings can be streamlined and hopefully largely automated before too long.

Projects have proven even trickier. Much legal informatics research takes the form of grant-funded projects, of which a great number, particularly in Europe, have been undertaken during the past decade. Political integration in Europe and democratization in many regions encouraged certain governments during the past two decades to fund applied research on legal information systems. Identifying and linking to all of these legal informatics projects seems important for enabling access to legal informatics scholarship. Such a process is quite labor intensive, however, because of the great number of such projects, the lack of a comprehensive list of them, and the many languages in which project documentation is written. A long-term goal of the Legal Information Systems site is to build a database of as many of these projects as can be identified, with links to project Websites, deliverables, and publications.

Since standards and protocols, such as those respecting descriptive metadata and knowledge representation, and data sets constitute additional key resources for legal informatics research, links to many of them have been collected on the Legal Information Systems site. Because many researchers in the field focus on a particular research topic or category of legal information, aggregations of resources on major topics in the field, such as e-rulemaking, evidence, and information behavior, to which the Legal Information Systems site has dedicated pages, and argumentation, to which Dr. Adam Wyner’s blog devotes several pages, may yield efficiencies for researchers. In addition, collections of resources on applied topics such as citation standards, computer-assisted legal research (CALR) services, court technology, the Free Access to Law movement (discussed here by Ginevra Peruginelli & Enrico Francesconi of ITTIG-CNR, with links to resources here), institutional repositories, instructional technology, law practice technology, and open access may be of use to researchers and practitioners alike.

II. Detecting a Communications Gap

From a preliminary scan of the field of legal informatics I’ve learned that legal informaticists and law librarians do not appear to be communicating to any significant extent. For example, law librarians seem to play little or no role at legal informatics conferences and are rarely published in legal informatics journals. (Sarah Rhodes & Dana Neacsu’s recent paper seems an exception.) This seems particularly odd, given that law libraries are developing some of today’s most innovative digital legal information systems, such as the Chesapeake Project Legal Information Archive (a project of the Georgetown University Law Library, the Maryland State Law Library, the Virginia State Law Library, and the Legal Information Preservation Alliance), the Law Library of Congress’s Global Legal Information Network (GLIN), the Harvard Law School Library’s Digital Collections, the digital law libraries created by the Rutgers Camden and Rutgers Newark law libraries, and the USC Law Library’s English Medieval Legal Documents Wiki. Law library scholarship — although it often addresses legal informatics topics such as legal citation (as in studies that reveal information resources utilized by courts), legal information behavior (as in the work of Dean Joan Howland & Nancy Lewis, Dr. Yolanda Jones, and Judith Lihosit ), and the functioning or design of legal information systems such as computer assisted legal research (CALR) services (as in recent studies by Julie Jones, John Doyle, and Dean Mason) — rather infrequently refers to legal informatics scholarship. That is, two communities of experts respecting the same subject — legal information systems — seem for the most part to be talking past each other.

Communication failure

Yet information sharing between law librarians and legal informaticists would substantially benefit both groups.   Law librarians would gain valuable insights into the functioning of the legal information systems they use every day and the likely direction of the legal information industry, as may be gleaned from recent monographs collecting conference papers in the field as well as from the program of the 2009 International Conference on Artificial Intelligence and Law (ICAIL 2009).   Those works show that the primary topics of recent legal informatics scholarship include argumentation and deontic logic (as discussed, for example, in recent dissertations by Dr. Adam Wyner & Dr. Régis Riveret); agent/multi-agent systems; decision support systems; document modeling; several natural language processing issues including multi-language systems, text mining including automated classification and indexing, summarization, segmentation, and information retrieval, as, for example, discussed in proceedings of the TREC Legal Track, and notably in the context of electronic discovery; other applied research topics, particularly concerning e-rulemaking, online dispute resolution, negotiation systems, digital rights management, electronic commerce and contracts, and evidence; and the use of XML, ontologies, and the development of the Semantic Web respecting legal information.

By cooperating with law librarians, legal informaticists for their part would gain access to expert users of legal information systems, quality input respecting the contexts of legal information use (ranging from the information lifecycle to the information behavior of lawyers), and ideas for further research.

Here are some specific suggestions respecting how law librarians could make meaningful contributions to legal informatics research.   First, law librarians could continue to perform legal information behavior research, building on the important recent activity in this area. Second, law librarians who are developing innovative legal information systems could present papers on those systems at legal informatics conferences and write articles about those systems for legal informatics journals.

Third, as expert users of legal information systems and close observers of lawyers, judges, law students, and lay users of legal information, law librarians could generate legal informatics research questions based on their experience and observations. For example, law librarians could recommend research on such little-studied but important legal information systems as conflict of interest control systems and bankruptcy claims agents’ Websites, or on the application of information science and computer science concepts to legal information systems errors, such as those arising from faulty legal drafting practices and overly complex statutory and regulatory schemes.

Fourth, law librarians could provide legal informaticists with expert practitioner and policy perspectives on issues that law librarians have prioritized as a profession, such as authentication, digital preservation, metadata content and management, and user interface design.   Fifth, law librarians could furnish legal informatics researchers with input respecting system capabilities from the vantage of an “expert user,” as Dr. Stephann Makri recently did by including law librarians in his study of lawyers’ information behavior.

Sixth, law librarians engaged in developing innovative digital legal information systems could partner with legal informaticists to study those systems. Seventh, law librarians who are also lawyers could contribute their knowledge of substantive and procedural law to legal informatics research projects, particularly where not all of the legal informaticists involved have legal training.

Finally, law librarians could draw on their in-depth knowledge of legal information systems and users to partner with legal informaticists on the design of research studies.   In particular, those law librarians with training in social science research methods could encourage legal informaticists to employ those methods in their studies of legal information systems, which might benefit from increased use of multiple methodologies.

Handshake

III. Bright Prospects

Greater cooperation between legal informaticists and law librarians would benefit both communities.  The Legal Information Systems site will be developed with an eye toward demonstrating and fostering that cooperation.

[NOTE: This post was updated on 22 August 2011 to reflect new URLs.]

Robert Richards  edits Legal Information Systems & Legal Informatics Resources and its accompanying blog , the Legal Informatics Blog, and  Twitter feed.

VoxPopuLII is edited by Judith Pratt.

Posted by Richards Robert at 7:00 am Tagged with: , , , , ,