LeCoPCR: Legal Concept-guided Prior Case Retrieval for European Court of Human Rights cases
This work addresses the challenge of finding relevant precedent cases for legal practitioners, representing an incremental improvement by incorporating legal concepts into retrieval models.
The paper tackled the problem of prior case retrieval for European Court of Human Rights cases by proposing LeCoPCR, which generates legal concepts from query facts to enhance semantic intent understanding, resulting in improved retrieval performance as demonstrated on the ECtHR-PCR dataset.
Prior case retrieval (PCR) is crucial for legal practitioners to find relevant precedent cases given the facts of a query case. Existing approaches often overlook the underlying semantic intent in determining relevance with respect to the query case. In this work, we propose LeCoPCR, a novel approach that explicitly generate intents in the form of legal concepts from a given query case facts and then augments the query with these concepts to enhance models understanding of semantic intent that dictates relavance. To overcome the unavailability of annotated legal concepts, we employ a weak supervision approach to extract key legal concepts from the reasoning section using Determinantal Point Process (DPP) to balance quality and diversity. Experimental results on the ECtHR-PCR dataset demonstrate the effectiveness of leveraging legal concepts and DPP-based key concept extraction.