DALE: Generative Data Augmentation for Low-Resource Legal NLP

Sreyan Ghosh, Chandra Kiran Reddy Evuru, Sonal Kumar, S Ramaneswaran, S Sakshi, Utkarsh Tyagi, Dinesh Manocha


Abstract
We present DALE, a novel and effective generative Data Augmentation framework for low-resource LEgal NLP. DALE addresses the challenges existing frameworks pose in generating effective data augmentations of legal documents - legal language, with its specialized vocabulary and complex semantics, morphology, and syntax, does not benefit from data augmentations that merely rephrase the source sentence. To address this, DALE, built on an Encoder-Decoder Language Model, is pre-trained on a novel unsupervised text denoising objective based on selective masking - our masking strategy exploits the domain-specific language characteristics of templatized legal documents to mask collocated spans of text. Denoising these spans help DALE acquire broad legal knowledge and develop the ability to generate coherent and diverse augmentations with novel contexts. Finally, DALE performs conditional generation to generate synthetic augmentations for low-resource Legal NLP tasks. We demonstrate the effectiveness of DALE on 13 datasets spanning 6 tasks and 4 low-resource settings. DALE outperforms all our baselines, including LLMs, qualitatively and quantitatively, with absolute improvements of 1%-50%.
Anthology ID:
2023.emnlp-main.528
Volume:
Proceedings of the 2023 Conference on Empirical Methods in Natural Language Processing
Month:
December
Year:
2023
Address:
Singapore
Editors:
Houda Bouamor, Juan Pino, Kalika Bali
Venue:
EMNLP
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
8511–8565
Language:
URL:
https://aclanthology.org/2023.emnlp-main.528
DOI:
10.18653/v1/2023.emnlp-main.528
Bibkey:
Cite (ACL):
Sreyan Ghosh, Chandra Kiran Reddy Evuru, Sonal Kumar, S Ramaneswaran, S Sakshi, Utkarsh Tyagi, and Dinesh Manocha. 2023. DALE: Generative Data Augmentation for Low-Resource Legal NLP. In Proceedings of the 2023 Conference on Empirical Methods in Natural Language Processing, pages 8511–8565, Singapore. Association for Computational Linguistics.
Cite (Informal):
DALE: Generative Data Augmentation for Low-Resource Legal NLP (Ghosh et al., EMNLP 2023)
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PDF:
https://aclanthology.org/2023.emnlp-main.528.pdf
Video:
 https://aclanthology.org/2023.emnlp-main.528.mp4