用确定性模型+模糊分级,让法律合规审查更透明可复现。
Deterministic Fuzzy Triage for Legal Compliance Classification and Evidence Retrieval
- 基于罗伯特双编码器与余弦相似度,实现可复现的合同条款检索
- 在测试集上达到NDCG@5 0.38-0.42,二分类任务AUC达0.98-0.99
- 通过可调阈值划分自动不合规、自动合规和需人工审查三类结果
法律团队越来越多地使用机器学习处理大量合同证据,但许多模型存在不透明、非确定性问题,难以与HIPAA或NERC-CIP等框架对齐。本文提出一种简单、可复现的方法:采用确定性双编码器与透明的模糊分级带。在ACORD基准上训练一个RoBERTa-base双编码器(512维投影,余弦相似度),用于分级条款检索;随后在基于CUAD的二分类合规数据集上微调。在单张NVIDIA A100 GPU上,五组随机种子(40-44)下,测试集上获得NDCG@5 0.38-0.42,NDCG@10 0.45-0.50,4星精确率@5约0.37。在高度不平衡的二分类任务中(正例占比约0.6%),模型达到AUC 0.98-0.99,F1 0.22-0.30,优于多数基线。进一步将合规评分映射为三类:自动不合规、自动合规、人工审核。通过验证集调优阈值,在保证自动决策错误率不超过2%的前提下最大化覆盖范围。系统最终由少量标量参数定义,具有种子稳定性。我们主张,确定性编码器、校准的模糊区间与显式误差约束,可在规则引擎与黑箱大模型之间提供实用折中方案,支持可解释的证据筛选、可复现的审计轨迹,并与法律审查概念建立明确映射。
原文摘要 · Abstract (English)
Legal teams increasingly use machine learning to triage large volumes of contractual evidence, but many models are opaque, non-deterministic, and difficult to align with frameworks such as HIPAA or NERC-CIP. We study a simple, reproducible alternative based on deterministic dual encoders and transparent fuzzy triage bands. We train a RoBERTa-base dual encoder with a 512-dimensional projection and cosine similarity on the ACORD benchmark for graded clause retrieval, then fine-tune it on a CUAD-derived binary compliance dataset. Across five random seeds (40-44) on a single NVIDIA A100 GPU, the model achieves ACORD-style retrieval performance of NDCG@5 0.38-0.42, NDCG@10 0.45-0.50, and 4-star Precision@5 about 0.37 on the test split. On CUAD-derived binary labels, it achieves AUC 0.98-0.99 and F1 0.22-0.30 depending on positive-class weighting, outperforming majority and random baselines in a highly imbalanced setting with a positive rate of about 0.6%. We then map scalar compliance scores into three regions: auto-noncompliant, auto-compliant, and human-review. Thresholds are tuned on validation data to maximize automatic decision coverage subject to an empirical error-rate constraint of at most 2% over auto-decided examples. The result is a seed-stable system summarized by a small number of scalar parameters. We argue that deterministic encoders, calibrated fuzzy bands, and explicit error constraints provide a practical middle ground between hand-crafted rules and opaque large language models, supporting explainable evidence triage, reproducible audit trails, and concrete mappings to legal review concepts.
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