Discovering Explanatory Sentences in Legal Case Decisions Using Pre-trained Language Models

TL;DR

This paper explores the use of pre-trained transformer models to identify explanatory sentences in legal case decisions, aiming to automate and improve the process of understanding complex legal concepts.

Contribution

It introduces a new dataset of legal sentences labeled for usefulness and demonstrates that transformer models outperform previous methods in identifying explanatory content.

Findings

Transformer models effectively detect useful explanatory sentences.

Legal explanatory sentences exhibit distinctive linguistic features.

Models outperform prior approaches in the task.

Abstract

Legal texts routinely use concepts that are difficult to understand. Lawyers elaborate on the meaning of such concepts by, among other things, carefully investigating how have they been used in past. Finding text snippets that mention a particular concept in a useful way is tedious, time-consuming, and, hence, expensive. We assembled a data set of 26,959 sentences, coming from legal case decisions, and labeled them in terms of their usefulness for explaining selected legal concepts. Using the dataset we study the effectiveness of transformer-based models pre-trained on large language corpora to detect which of the sentences are useful. In light of models' predictions, we analyze various linguistic properties of the explanatory sentences as well as their relationship to the legal concept that needs to be explained. We show that the transformer-based models are capable of learning surprisingly sophisticated features and outperform the prior approaches to the task.