Abstract
Machine learning shows promise in predicting the outcome of legal cases, but
most research has concentrated on civil law cases rather than case law systems.
We identified two unique challenges in making legal case outcome predictions
with case law. First, it is crucial to identify relevant precedent cases that
serve as fundamental evidence for judges during decision-making. Second, it is
necessary to consider the evolution of legal principles over time, as early
cases may adhere to different legal contexts. In this paper, we proposed a new
framework named PILOT (PredictIng Legal case OuTcome) for case outcome
prediction. It comprises two modules for relevant case retrieval and temporal
pattern handling, respectively. To benchmark the performance of existing legal
case outcome prediction models, we curated a dataset from a large-scale case
law database. We demonstrate the importance of accurately identifying precedent
cases and mitigating the temporal shift when making predictions for case law,
as our method shows a significant improvement over the prior methods that focus
on civil law case outcome predictions.