This project addresses key challenges in processing legal documents, specifically:
Rhetorical Role Segmentation: Tackling class imbalance in datasets to enhance the model's ability to detect minority rhetorical roles in legal texts.
Summarization: Generating high-quality summaries using a hybrid extractive-abstractive approach to capture crucial legal entities and condense information.
Model Details
Rhetorical Role Segmentation
Objective: Segment legal text based on rhetorical roles (e.g., Facts, Arguments, Rulings).
Challenge: Imbalanced class labels, with majority classes overshadowing minority classes.
Solution: A class-weighted oversampling method that calculates an oversampling rate based on the frequency distribution of class labels, ensuring adequate representation of minority classes.
Model Architecture
This model is trained to distinguish 13 class labels in legal text, utilizing class-weighted oversampling to prevent overfitting to the majority classes.
Data Augmentation
A normalized frequency distribution of class labels was created, as visualized in Figure 5: Unbalanced Dataset.
Using this distribution, we applied a class-weighted oversampling rate to increase minority class samples proportionally.
Summarization
Objective: Summarize legal documents by retaining essential legal entities and reducing information redundancy.
Approach:
Extractive Step: An NER model tailored for legal documents extracts sentences with named entities, producing an initial summary.
Abstractive Step: A fine-tuned Longformer Encoder-Decoder (LED) model refines the extractive summary to create a concise output.
Model Architecture
The extractive component utilizes a legal-specific Named Entity Recognition (NER) model.
The abstractive summarization is achieved using a pre-trained LED model on Hugging Face, further fine-tuned on legal data.
Evaluation
Each component was evaluated using ROUGE metrics, with the hybrid approach demonstrating superior performance in terms of informativeness and conciseness.
