When Fairness Isn't Statistical: The Limits of Machine Learning in Evaluating Legal Reasoning

Fuente: arXiv
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Main Authors: Barale, Claire, Rovatsos, Michael, Bhuta, Nehal
Format: Preprint
Published: 2025
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author Barale, Claire
Rovatsos, Michael
Bhuta, Nehal
author_facet Barale, Claire
Rovatsos, Michael
Bhuta, Nehal
contents Legal decisions are increasingly evaluated for fairness, consistency, and bias using machine learning (ML) techniques. In high-stakes domains like refugee adjudication, such methods are often applied to detect disparities in outcomes. Yet it remains unclear whether statistical methods can meaningfully assess fairness in legal contexts shaped by discretion, normative complexity, and limited ground truth. In this paper, we empirically evaluate three common ML approaches (feature-based analysis, semantic clustering, and predictive modeling) on a large, real-world dataset of 59,000+ Canadian refugee decisions (AsyLex). Our experiments show that these methods produce divergent and sometimes contradictory signals, that predictive modeling often depends on contextual and procedural features rather than legal features, and that semantic clustering fails to capture substantive legal reasoning. We show limitations of statistical fairness evaluation, challenge the assumption that statistical regularity equates to fairness, and argue that current computational approaches fall short of evaluating fairness in legally discretionary domains. We argue that evaluating fairness in law requires methods grounded not only in data, but in legal reasoning and institutional context.
format Preprint
id arxiv_https___arxiv_org_abs_2506_03913
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle When Fairness Isn't Statistical: The Limits of Machine Learning in Evaluating Legal Reasoning
Barale, Claire
Rovatsos, Michael
Bhuta, Nehal
Computation and Language
Machine Learning
Legal decisions are increasingly evaluated for fairness, consistency, and bias using machine learning (ML) techniques. In high-stakes domains like refugee adjudication, such methods are often applied to detect disparities in outcomes. Yet it remains unclear whether statistical methods can meaningfully assess fairness in legal contexts shaped by discretion, normative complexity, and limited ground truth. In this paper, we empirically evaluate three common ML approaches (feature-based analysis, semantic clustering, and predictive modeling) on a large, real-world dataset of 59,000+ Canadian refugee decisions (AsyLex). Our experiments show that these methods produce divergent and sometimes contradictory signals, that predictive modeling often depends on contextual and procedural features rather than legal features, and that semantic clustering fails to capture substantive legal reasoning. We show limitations of statistical fairness evaluation, challenge the assumption that statistical regularity equates to fairness, and argue that current computational approaches fall short of evaluating fairness in legally discretionary domains. We argue that evaluating fairness in law requires methods grounded not only in data, but in legal reasoning and institutional context.
title When Fairness Isn't Statistical: The Limits of Machine Learning in Evaluating Legal Reasoning
topic Computation and Language
Machine Learning
url https://arxiv.org/abs/2506.03913