Cornell University
Library
Cornell UniversityLibrary

eCommons

Help
Log In(current)
  1. Home
  2. Cornell University Graduate School
  3. Cornell Theses and Dissertations
  4. LEGAL REASONING WITH SEARCH-AUGMENTED REINFORCEMENT LEARNING: A MULTI-TASK FRAMEWORK

LEGAL REASONING WITH SEARCH-AUGMENTED REINFORCEMENT LEARNING: A MULTI-TASK FRAMEWORK

File(s)
Akinboro_cornell_0058O_12647.pdf (450.19 KB)
Permanent Link(s)
https://doi.org/10.7298/qegw-g305
https://hdl.handle.net/1813/126292
Collections
Cornell Theses and Dissertations
Author
Akinboro, David
Abstract

Large language models hallucinate in 69% to 88% of legal queries, yet current systems only access external tools at inference time, never learning legal research methodology during training. This thesis presents a search-augmented reinforcement learning framework that integrates 18 specialized tools directly into the training loop via a smart Model Context Protocol client. The framework introduces four contributions: multi-tool training with a 9-call episodic constraint, multi-task reward routing using LLM judge ensembles across four legal task types, US jurisdiction compliance gating across all 50 states plus the federal system, and an attention-based interpretability framework for mapping legal reasoning patterns. Implemented with Qwen 2.5 3B and GRPO optimization on 8 A100 GPUs, the system achieves a 10.5 percentage point improvement over baselines on LegalBench (59.6% vs. 49.7%), 97% jurisdictional compliance, and 0.72 Spearman correlation between model attention and expert fact importance rankings.

Description
88 pages
Date Issued
2026-05
Keywords
interpretability
•
large language models
•
legal reasoning
•
multi-task learning
•
reinforcement learning
•
retrieval-augmented generation
Committee Chair
Cardie, Claire
Committee Member
Manzoor, Emaad
Degree Discipline
Computer Science
Degree Name
M.S., Computer Science
Degree Level
Master of Science
Rights
Attribution 4.0 International
Rights URI
https://creativecommons.org/licenses/by/4.0/
Type
dissertation or thesis

Site Statistics | Help

About eCommons | Policies | Terms of use | Contact Us

copyright © 2002-2026 Cornell University Library | Privacy | Web Accessibility Assistance