Harvey, Spellbook, Legora + TR Already Have It – Artificial Lawyer

GPT-5 has finally launched today and Harvey, Spellbook, Legora, and Thomson Reuters have had early access. They give Artificial Lawyer their verdicts on the new LLM that’s expected to have a big impact on the legal tech world.

Winston Weinberg, CEO of Harvey, told Artificial Lawyer: ‘GPT‑5 lands at the perfect moment. First, its stronger reasoning and tool orchestration will enable us to support more complex workflows that can branch, loop, and self-correct – all while keeping users in the driver’s seat through interaction and verification.  

‘Second, its long-form writing capabilities allow us to move beyond generating paragraphs to composing complete, multi-section documents that exhibit structural integrity and internal consistency, conforming to specific precedents and drafting conventions. 

‘Early access through OpenAI helped us turn these two large improvements into something powerful for our customers.’

(The company has also just announced its latest office – this time in Canada.)

Meanwhile, Thomson Reuters’ Joel Hron, Chief Technology Officer, told Artificial Lawyer: ‘Determining whether a mischaracterization has occurred isn’t just about matching facts ­– it requires evaluating a statement within the full context of a legal brief, the cited case, and the relationship between them. That’s a multi-layered reasoning task across multiple documents.

‘When we shifted to a reasoning model like OpenAI’s GPT-o3, we saw significantly more nuanced and accurate explanations. Now, as we test GPT-5, we’re building on that foundation – pushing for even deeper contextual understanding in high-stakes legal analysis.’

Meanwhile, Spellbook, another legal genAI pioneer, has also been working with OpenAI in relation to GPT-5. Scott Stevenson, CEO, and team, told Artificial Lawyer in an extended statement to this site:

‘GPT-5 introduces a new level of sophistication in identifying subtle contractual risks. In internal tests, Spellbook found GPT-5 was the first model to consistently flag many nuanced, jurisdiction-specific compliance issues – that escaped earlier models like Claude 4 and GPT-4o.

‘The model demonstrates a deeper capacity to cross-reference jurisdiction, statutory requirements, and clause language, enabling a new level of automated legal diligence. Spellbook also noted significant advancements in GPT-5’s fluency with security, compliance, and data protection language, making it especially effective in refining and expanding enterprise-grade DPAs.

‘Beyond issue spotting, GPT-5 is setting a new benchmark for precision editing in complex Word documents—a critical task for transactional lawyers. Traditional generative models often regenerate entire sections or struggle with real-world Word document formatting. In contrast, GPT-5 is able to:

Make surgical edits that preserve surrounding context

Reliably populate key fields and remove placeholders

Accurately navigate and revise tabular structures in Word document agreements

‘Transactional lawyers rarely draft from scratch. They work with legacy precedents that are often 50+ pages, full of defined terms, interlinked clauses, and embedded tables. GPT-5 is the first model we’ve seen that can reliably handle these realities.

‘Early results suggest GPT-5 will power an emerging class of revision-based workflows where AI acts more like an associate, carefully refining documents rather than spitting out isolated language.

‘GPT-5 is now live in Spellbook Associate, Spellbook’s agentic drafting product, with phased deployment underway across Spellbook’s broader review functionality. The team is monitoring ‘suggestion acceptance rates’ closely to optimize GPT-5’s rollout.’

Spellbook also added a comment from Marc Manara, Head of Startups at OpenAI, who said: ‘Working with Spellbook on GPT-5 is the latest example of how their feedback and early testing will help us identify the API’s optimal impact where it matters most for transactional lawyers.’

And to conclude, Max Junestrand, CEO at Legora, added: ‘As the capabilities, speed, and intelligence of AI continue to get exponentially better, we’re committed to keeping pace with this rapid speed of innovation and ensuring our clients feel the benefits straight away.

‘One of the earliest technical decisions we made as a company was to be model-agnostic. This means we work closely with all the top labs, always use the models best suited for the exacting standards of legal work, and can be the fastest to react to the constant changes in the AI space.’

Is this a big deal?

Well, consider this point: all of the genAI skills that we now see in the market are primarily based on what the underlying LLMs can do – and OpenAI’s models have been fundamental to the growth of much of the legal AI market since November 2022.

If those models get better – especially in relation to text analysis – then that in turn filters through to the legal tech tools, allowing for greater subtlety in responses and better accuracy (albeit that term is subjective in relation to the task demanded).

Overall, this is a win for the legal and legal tech markets, as the improved model’s capabilities will be felt across all parts of this sector. Harvey, Spellbook, Legora, Thomson Reuters and no doubt some other companies that have been closely involved with the roll-out will have a head start, but soon enough all the other companies in this sector will bring GPT-5 aboard as well.

And then we will all be talking about GPT-6……Plus, other major LLM makers, from Google, to Anthropic, to DeepSeek and more, will all seek to respond with their own improvements. But, this huge push to improve genAI – with billions upon billions of dollars invested in achieving this goal, all leads to the point above: better results for the legal market, a segment of the economy that lives and breathes text and its meaning.

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Legal Innovators Conferences in New York and London – Both In November ’25

If you’d like to stay ahead of the legal AI curve….then come along to Legal Innovators New York, Nov 19 + 20, where the brightest minds will be sharing their insights on where we are now and where we are heading. 

And also, Legal Innovators UK – Nov 4 + 5 + 6

Both events, as always, are organised by the awesome Cosmonauts team! 

Please get in contact with them if you’d like to take part.