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Thomson Reuters builds its own legal LLM on top of Qwen and open-weights the small version
Thomson Reuters launched Thomson 1.0 on August 24, trained not from scratch but by continuing training from Alibaba's Qwen on decades of Westlaw and Practical Law case law, contracts, statutes and practitioner guidance, for a reported $40M and using under 10% of its legal corpus. The open-weight Thomson-1.0-Small on Hugging Face is a 35B-total/3B-active MoE built from Qwen3.6-35B-A3B, claiming 79.9% on Stanford LegalBench and 74.6% overall average, under a restrictive Polyform-Strict license. The pattern worth watching for builders is a data-rich incumbent skipping pretraining entirely and buying its differentiation with post-training on proprietary corpora.
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