Coupling Local Context and Global Semantic Prototypes via a Hierarchical Architecture for Rhetorical Roles Labeling
Organizations: Nantes Université, École Centrale Nantes, CNRS, LS2N, UMR 6004, F-44000 Nantes, France · University of Lorraine, France
Abstract
Rhetorical Role Labeling (RRL) identifies the functional role of each sentence in a document, a key task for discourse understanding in domains such as law and medicine. While hierarchical models capture local dependencies effectively, they are limited in modeling global, corpus-level features. To address this limitation, we propose two prototype-based methods that integrate local context with global representations. Prototype-Based Regularization (PBR) learns soft prototypes through a distance-based auxiliary loss to structure the latent space, while Prototype-Conditioned Modulation (PCM) constructs corpus-level prototypes and injects them during training and inference. Given the scarcity of RRL resources, we introduce SCOTUS-Law, the first dataset of U.S. Supreme Court opinions annotated with rhetorical roles at three levels of granularity: category, rhetorical function, and step. Experiments on legal, medical, and scientific benchmarks show consistent improvements over strong baselines, with 4 Macro-F1 gains on low-frequency roles. We further analyze the implications in the era of Large Language Models and complement our findings with expert evaluation.
Figures & tables
| Corpus-level statistics | |||
|---|---|---|---|
| Statistic | Train | Dev | Test |
| # Documents | 144 | 18 | 18 |
| Total # Sentences | 21,396 | 2,450 | 2,481 |
| Avg. # Sentences / Doc | 148.58 | 136.11 | 137.83 |
| Avg. # Tokens / Sentence | 22.95 | 21.43 | 22.15 |
| Sentence distribution by rhetorical function | |||
| Legal | Medical | Scientific | ||||||||||||
| Scotus Category | Scotus RF | Scotus Steps | LegalEval | DeepRhole | PubMed | CS-Abstracts | ||||||||
| mF1 | wF1 | mF1 | wF1 | mF1 | wF1 | mF1 | wF1 | mF1 | wF1 | mF1 | wF1 | mF1 | wF1 | |
| Baseline (HSLN) | 82.22 | 88.35 | 61.36 | 78.81 | 46.70 | 63.21 | 78.82 | 90.94 | 44.24 | 50.51 | 87.01 | 91.09 | 68.55 | 75.08 |
| Mind T.y.s.s. et al. (2024) | 83.46 | 89.20 | 62.67 | 79.07 | 45.24 | 62.78 | 79.80 | 91.25 | 45.30 | 50.93 | 87.67 | 91.86 | 69.19 | 76.91 |
| PBR | 83.69 ‡ | 89.75 ‡ | 65.75 ‡ | 80.31 ‡ | 50.48 ‡ | 65.73 ‡ | 82.50 ‡ | 93.17 ‡ | 44.96 † | 51.11 † | 88.86 ‡ | 92.91 ‡ | 71.10 ‡ | 78.09 ‡ |
| PCM (Full Sampling) | 83.96 ‡ | 89.80 ‡ | 67.53 ‡ | 80.64 ‡ | 54.03 ‡ | 67.54 ‡ | 81.41 ‡ | 91.21 | 47.13 ‡ | 55.54 ‡ | 87.19 | 91.89 | 69.84 | 76.66 |
| Rhetorical Function | % | Baseline | +PCM | |
|---|---|---|---|---|
| Accepting arguments/a reasoning | 41.75 | |||
| Announcing | 7.95 | |||
| Citing | 3.93 | |||
| Describing | 0.37 | |||
| Evaluating the impact of the decision | 0.00 | |||
| Giving instructions to competent courts | 3.83 |
| Legal | Medical | Scientific | ||||
| SCOTUS RF | PubMed | CS-Abstracts | ||||
| mF1 | wF1 | mF1 | wF1 | mF1 | wF1 | |
| DeepSeek-70B | 65.20 | 75.20 | 81.03 | 86.67 | 64.92 | 72.60 |
| Meta-Llama3-8B | 66.78 | 75.09 | 82.51 | 87.63 | 67.39 | 74.59 |
| Mistral-7B | 70.29 | 76.61 | 81.86 | 87.20 | 62.24 | 70.61 |
| Qwen3-8B | 69.36 | 75.53 | 81.73 | 87.26 | 65.93 | 74.93 |
| Input Excerpt | Confused Role Pair | Gold Label | Baseline Prediction | PCM Prediction | Error Reduction | Expert Assessment |
|---|---|---|---|---|---|---|
| As we have explained , failure to comply with §262(l)(2)(A) is not an act of artificial infringement. | Recalling Stating the Court’s reasoning | Recalling | Stating the Court’s reasoning | Recalling | 19.75% | This case is ambiguous because “As we have explained” signals a backward reference, while the remainder conveys a definitive judicial conclusion, typical of Stating the Court’s reasoning. |
| Thus, in Los Angeles Cloak Joint Board ILGWU (Helen Rose Co.), 127 N. L. R. B. 1543 (1960), the Board held that §8(b)(1)(B) barred a union from picketing a company in an attempt to force the employer to… | Describing Recalling | Recalling | Describing | Recalling | 6.56% | The difficulty arises because “the Board held that” points to recalling a precedent, yet the remainder paraphrases substantive content neutrally, resembling Describing. |
| The American Bar Association recommends defense counsel “promptly communicate and explain to the defendant all plea offers made by the prosecuting attorney,” ABA Standards for Criminal Justice, Pleas of Guilty 14–3.2(a) (3d ed. 1999), | Quoting Recalling | Recalling | Quoting | Recalling | 33.33% | Ambiguity stems from combining an attribution verb (“recommends”) with a direct quotation, blending narrative recall with verbatim citation and blurring the distinction between Recalling and Quoting. |
| Model | Annotation Difficulty (Likert Scale) | |||
|---|---|---|---|---|
| Easy | Rather easy | Rather difficult | Difficult | |
| PCM (Best) | 100 | 79.62 | 61.53 | 16.66 |
Appendix figures & tables7 assets
Supplementary material from the paper’s appendix.
Appendix
| Dataset | Source | Domain | Language | # Docs | # Sents | Labels |
|---|---|---|---|---|---|---|
| Scotus Category | Ours | Legal (U.S.) | English | 180 | 26,327 | 5 |
| Scotus RF | Ours | Legal (U.S.) | English | 180 | 26,327 | 13 |
| Scotus Steps | Ours | Legal (U.S.) | English | 180 | 26,327 | 35 |
| LegalEval | Kalamkar et al. (2022) | Legal (India) | English | 214 | 31,865 | 13 |
| DeepRhole | Bhattacharya et al. (2023a) | Legal (India) | English | 50 | 9,380 | 7 |
| PubMed | Dernoncourt and Lee (2017) | Medical | English | 20,000 | 227,000 | 5 |
| Method | Scotus RF | LegalEval | PubMed |
|---|---|---|---|
| Linear Fusion | 80.89 | 91.62 | 91.91 |
| Conditional Layer Norm | 78.11 | 87.49 | 92.74 |
| Cross-Attention Fusion | 79.30 | 87.74 | 92.20 |
| Feature-wise Linear Mod. | 74.71 | 76.74 | 92.74 |
| Gated Residual Addition | 79.58 | 89.06 | 92.79 |
Prototype Learning
Prototype learning represents data with representative examples or feature centers to support classification, adaptation, anomaly detection, and interpretable predictions.
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