BenGER: Benchmarking LLM Systems on Subsumption-Based Legal Reasoning in German Law

Sebastian Nagl, Ann-Kristin Mayrhofer, Martin Heidebach, Aleyna Koçak, Anne Zettelmeier, Elly Breu, Angelina Greiner, Sofija Milijas, Matthias Grabmair


Abstract
We introduce BenGER (Benchmark for German Law), a benchmark and dataset for subsumption-based legal reasoning in German law. It combines 596 exam-style free-text case tasks across several levels of legal education with 531 short doctrinal reasoning tasks, and a controlled subset adds timed human solutions written both unaided and in human-AI co-creation. We evaluate 12 contemporary LLM systems (closed flagship, efficiency-oriented, and open-weight) with a rubric-aligned LLM-as-a-Judge, which we cross-validate against a multi-rater human layer (three blind reviews per solution) and across six LLM judges. Our results show that closed-flagship systems lead across all three corpora, that human-AI co-creation measurably improves on unaided human work, and that the judge tracks human grading at Pearson r=0.76 and Cohen’s κ=0.60, with rankings stable across judges and two judges from independent providers clearing the Calderon single-reviewer replacement bar on human-authored solutions.
Anthology ID:
2026.findings-emnlp.1266
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
26759–26794
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.1266/
DOI:
10.18653/2026.findings-emnlp.1266
Bibkey:
Cite (ACL):
Sebastian Nagl, Ann-Kristin Mayrhofer, Martin Heidebach, Aleyna Koçak, Anne Zettelmeier, Elly Breu, Angelina Greiner, Sofija Milijas, and Matthias Grabmair. 2026. BenGER: Benchmarking LLM Systems on Subsumption-Based Legal Reasoning in German Law. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 26759–26794, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
BenGER: Benchmarking LLM Systems on Subsumption-Based Legal Reasoning in German Law (Nagl et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.1266.pdf