Exploration of Domain Relevance by Legal Professionals in Information Retrieval Systems

Abstract This paper, written by Gineke Wiggers, Suzan Verberne, Gerrit-Jan Zwenne and Wouter Van Loon, addresses the concept of ‘relevance’ in relation to legal information retrieval (IR). They investigate whether the conceptual framework of relevance in legal IR, as described by Van Opijnen and Santos in their paper published in 2017, can be confirmed in practice.1 The research is conducted with a user questionnaire in which users of a legal IR system had to choose which of two results they would like to see ranked higher for a query and were asked to provide a reason for their choice. To avoid questions with an obvious answer and extract as much information as possible about the reasoning process, the search results were chosen to differ on relevance factors from the literature, where one result scores high on one factor, and the other on another factor. The questionnaire had eleven pairs of search results. A total of 43 legal professionals participated consisting of 14 legal information specialists, 6 legal scholars and 23 legal practitioners. The results confirmed the existence of domain relevance as described in the theoretical framework by Van Opijnen and Santos as published in 2017.2 Based on the factors mentioned by the respondents, the authors of this paper concluded that document type, recency, level of depth, legal hierarchy, authority, usability and whether a document is annotated are factors of domain relevance that are largely independent of the task context. The authors also investigated whether different sub-groups of users of legal IR systems (legal information specialists who are searching for others, legal scholars and also for legal practitioners) differ in terms of the factors they consider in judging the relevance of legal documents outside of a task context. Using a PERMANOVA there was found to be no significant difference in the factors reported by these groups. At this moment there is no reason to treat these sub-groups differently in legal IR systems.