The advent of large language models (LLMs)  and their adoption by the legal community has given rise to the question: what types of legal reasoning can LLMs perform? To enable greater study of this question, we presentLegalBench: a collaboratively constructed legal reasoning benchmark consisting of 162 tasks covering six different types of legal reasoning.LegalBenchwas built through an interdisciplinary process, in which we collected tasks designed and hand-crafted by legal professionals. Because these subject matter experts took a leading role in construction, tasks either measure legal reasoning capabilities that are practically useful, or measure reasoning skills that lawyers find interesting. To enable cross-disciplinary conversations about LLMs in the law, we additionally show how popular legal frameworks for describing legal reasoning—which distinguish between its many forms—correspond toLegalBenchtasks, thus giving lawyers and LLM developers a common vocabulary. This paper describesLegalBench, presents an empirical evaluation of 20 open-source and commercial LLMs, and illustrates the types of research explorationsLegalBenchenables.