Dataset Card for LexBOE

Dataset summary

LexBOE is a Spanish legal text classification dataset built from articles extracted from the Boletín Oficial del Estado (BOE), the official source of legislation and administrative acts in Spain. The articles included in the dataset were published between 2022 and 2024. LexBOE reflects contemporary legal-administrative language and is intended for the training and evaluation of language models on legal text classification tasks.

• Curated by: Barcelona Supercomputing Center (BSC)
• Funded by: ALIA
• Language(s) (NLP): Spanish (es)
• License: CC BY 4.0

Dataset Details

Dataset Description

LexBOE was constructed through systematic extraction of articles and metadata using the official BOE API. The original metadata was analyzed and then consolidated into a set of 14 legal categories. These categories are as follows:

Label	Description
Funcionarios y Personal	Public employment and civil service
Normativas	Laws and regulations
Administración	Administrative organization and procedures
Educación	Education systems, institutions, and policies
Economía	Economic and financial matters
Energía	Energy policy and infrastructure
Judicial	Courts, legal proceedings, and judicial bodies
Cultura	Cultural institutions and activities
Salud	Public health and healthcare
Transporte	Transport systems and infrastructure
Fuerzas	Security forces and defense-related matters
Vivienda	Housing and urban development

LexBOE also applies a pseudo-anonymization process in which sensitive personal information is replaced with formally and semantically equivalent values, preserving the linguistic structure of the original texts.

Dataset Structure

An example of instance looks as follows:

{
  "id": "BOE-A-2024-23238",
  "sentence": "Advertido error en la Resolución de 11 de octubre de 2024, de la Universidad Pablo de Olavide, de Sevilla, por la que se convoca Concurso de Acceso a plazas de Cuerpos Docentes Universitarios, publicada en el «Boletín Oficial del Estado» el 23 de octubre de 2024, se transcribe a continuación la oportuna rectificación:\nEn la página 135662, en el apartado 1. Legislación, donde dice:\n«Los concursos se regirán por lo dispuesto en el artículo 71.1».\nDebe decir:\n«Los concursos se regirán por lo dispuesto en el artículo 71.2».\nSevilla, 31 de octubre de 2024.–El Rector, Francisco Oliva Blázquez.",
  "label": "Educación"
}

Dataset Sources

The texts in LexBOE were extracted from the Boletín Oficial del Estado (BOE) using the official BOE public API.

Uses

Direct Use

LexBOE is intended for research and development in legal natural language processing, particularly for text classification tasks in Spanish. Typical use cases include:

• Training and evaluating encoder-based models on legal text classification
• Benchmarking Spanish legal language understanding
• Studying domain adaptation and representation learning in the legal domain
• Developing downstream legal NLP applications in a research context

Out-of-Scope Use

LexBOE is not intended for:

• Legal advice, decision-making, or interpretation of legal obligations
• Use in production systems without additional validation and domain-specific safeguards
• Applications that attempt to recover or infer real personal or institutional identities from the texts
• Any use that violates applicable data protection regulations or ethical guidelines

Funding

This work is funded by the Ministerio para la Transformación Digital y de la Función Pública - Funded by EU – NextGenerationEU within the framework of the project Desarrollo de Modelos ALIA.

Acknowledgements

This dataset is released in conjunction with the work presented in Tamayo Mela et al., MrBERT: Modern Multilingual Encoders via Vocabulary, Domain, and Dimensional Adaptation, as part of the evaluation of domain-adapted encoder models in the legal domain.

Citation

@article{tamayo2026mrbert,
  title={MrBERT: Modern Multilingual Encoders via Vocabulary, Domain, and Dimensional Adaptation},
  author={Tamayo, Daniel and Lacunza, I{\~n}aki and Rivera-Hidalgo, Paula and Da Dalt, Severino and Aula-Blasco, Javier and Gonzalez-Agirre, Aitor and Villegas, Marta},
  journal={arXiv preprint arXiv:2602.21379},
  year={2026}
}

Contact point

Language Technologies Lab (langtech@bsc.es) at the Barcelona Supercomputing Center (BSC).