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Joel Hron

Thomson Reuters

  • 1 episode on Chain of Thought
  • 3 topics covered
  • 1 full transcript
  • Aug 2026 first on the show
Joel Hron

Joel Hron is the chief technology officer of Thomson Reuters, where his teams build Westlaw, Practical Law, and CoCounsel for professionals in more than 100 countries. He joined Chain of Thought at the launch of Thomson, the company’s own legal AI model, to explain why a 175-year-old company chose to train its own model for about $40 million rather than only rent frontier intelligence, and how rebuilding CoCounsel around agent-native tools moved one-shot accuracy from 25% to over 70%.

Cover art for Thomson 1: The New $40M Legal AI Model | Thomson Reuters Joel Hron

Latest episode with Joel Hron · EP 69

Thomson 1: The New $40M Legal AI Model | Thomson Reuters Joel Hron

Joel Hron, Thomson Reuters ·

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What the conversations cover

These notes summarize the episodes featuring Joel Hron, including other speakers in panel conversations. Follow a source link to read the discussion in context.

EP 69 Thomson 1: The New $40M Legal AI Model | Thomson Reuters Joel Hron

  • Joel Hron describes selecting material from Thomson Reuters’ legal, tax, and news collections for continued pretraining. At the time of the interview, he said less than 10% of that corpus had been used for this training step. Transcript at 14:37
  • Hron attributes CoCounsel’s reported move from about 25% to above 70% on its internal legal-task benchmark to rebuilding its agent architecture and tools. He separates that improvement from the subsequent work to train the Thomson model. Transcript at 17:37
  • Hron describes a citation ledger that tracks cases the agent has inspected. He distinguishes fabricated case names from subtler errors in interpreting real law, such as reading a judicial opinion as a fact or applying a ruling too broadly. Transcript at 41:54

In their words

Yeah, yeah. I mean, maybe more actually. We were flying carrier pigeons across the sea to deliver news way back in the day. So yeah, pretty old. I mean, we're probably one of the oldest companies on the planet. So I would venture to say the odds are pretty good we might be the oldest, but I don't want to state something I factually don't know.

Joel Hron Thomson 1: The New $40M Legal AI Model | Thomson Reuters Joel Hron · 8:31

Transcript excerpts; ellipses mark omitted words. Some automatically selected quotes have filler words removed.