Magnus Sesodia

Chandler Smith, Magnus Sesodia, Friedrich Lindenberg et al.

We release OpenSanctions Pairs, a large-scale entity matching benchmark derived from real-world international sanctions aggregation and analyst deduplication. The dataset contains 755,540 labeled pairs spanning 293 heterogeneous sources across 31 countries, with multilingual and cross-script names, noisy and missing attributes, and set-valued fields typical of compliance workflows. We benchmark a production rule-based matcher (nomenklatura RegressionV1 algorithm) against open- and closed-source LLMs in zero- and few-shot settings. Off-the-shelf LLMs substantially outperform the production rule-based baseline (91.33\% F1), reaching up to 98.95\% F1 (GPT-4o) and 98.23\% F1 with a locally deployable open model (DeepSeek-R1-Distill-Qwen-14B). DSPy MIPROv2 prompt optimization yields consistent but modest gains, while adding in-context examples provides little additional benefit and can degrade performance. Error analysis shows complementary failure modes: the rule-based system over-matches (high false positives), whereas LLMs primarily fail on cross-script transliteration and minor identifier/date inconsistencies. These results indicate that pairwise matching performance is approaching a practical ceiling in this setting, and motivate shifting effort toward pipeline components such as blocking, clustering, and uncertainty-aware review. Code available at https://github.com/chansmi/OSINT_entity_resolution

Magnus Sesodia, Alina Petrova, John Armour et al.

Legal systems worldwide continue to struggle with overwhelming caseloads, limited judicial resources, and growing complexities in legal proceedings. Artificial intelligence (AI) offers a promising solution, with Legal Judgment Prediction (LJP) -- the practice of predicting a court's decision from the case facts -- emerging as a key research area. However, existing datasets often formulate the task of LJP unrealistically, not reflecting its true difficulty. They also lack high-quality annotation essential for legal reasoning and explainability. To address these shortcomings, we introduce AnnoCaseLaw, a first-of-its-kind dataset of 471 meticulously annotated U.S. Appeals Court negligence cases. Each case is enriched with comprehensive, expert-labeled annotations that highlight key components of judicial decision making, along with relevant legal concepts. Our dataset lays the groundwork for more human-aligned, explainable LJP models. We define three legally relevant tasks: (1) judgment prediction; (2) concept identification; and (3) automated case annotation, and establish a performance baseline using industry-leading large language models (LLMs). Our results demonstrate that LJP remains a formidable task, with application of legal precedent proving particularly difficult. Code and data are available at https://github.com/anonymouspolar1/annocaselaw.