isaacus/mleb-legal-rag-bench

Legal RAG Bench (MLEB version)

This is the version of the Legal RAG Bench evaluation dataset used in the Massive Legal Embedding Benchmark (MLEB) by Isaacus.

This dataset tests the ability of information retrieval models to retrieve relevant passages to complex, meaningfully challenging, reasoning-intensive questions about Victorian criminal law.

If you are looking for Legal RAG Bench proper, you may find it here.

Structure 🗂️

As per the MTEB information retrieval dataset format, this dataset comprises three splits: default, corpus and queries.

The default split pairs questions (query-id) with relevant passages (corpus-id), each pair having a score of 1.

The corpus split contains passages, with the text of a passage being stored in the text key and its id being stored in the _id key. There is also a title column, which is deliberately set to an empty string in all cases for compatibility with the mteb library.

The queries split contains questions, with the text of a question being stored in the text key and its id being stored in the _id key.

Methodology 🧪

To understand how Legal RAG Bench itself was created, refer to its documentation.

This dataset was formatted by taking the test split of Legal RAG Bench, treating questions as anchors and relevant passages as positive passages, and adding irrelevant passages to the global passage corpus.

License 📜

This dataset is licensed under CC BY NC 4.0 which allows for non-commercial use of this dataset as long as appropriate attribution is made to it.

Citation 🔖

If you use this dataset, please cite the Massive Legal Embeddings Benchmark (MLEB) as well. A preprint for Legal RAG Bench will be published before 27 February 2026 at the latest.

@misc{butler2026legalragbench,
      title={Legal RAG Bench},
      author={Abdur-Rahman Butler and Umar Butler},
      year={2026},
      note={Preprint forthcoming.}
}

@misc{butler2025massivelegalembeddingbenchmark,
      title={The Massive Legal Embedding Benchmark (MLEB)}, 
      author={Umar Butler and Abdur-Rahman Butler and Adrian Lucas Malec},
      year={2025},
      eprint={2510.19365},
      archivePrefix={arXiv},
      primaryClass={cs.CL},
      url={https://arxiv.org/abs/2510.19365}, 
}