Whether to buy specialist legal AI when the firm already pays for a general assistant comes up in almost every conversation about budget. On 23 July Microsoft answered that question for its own lawyers. Its Corporate, External and Legal Affairs team, the group that runs the company's legal and compliance work, took on the Harvey platform across those operations while continuing to run Microsoft 365 Copilot, the general assistant Microsoft builds and sells itself.
What Microsoft did
Harvey and Microsoft announced an expanded arrangement on 23 July 2026. The legal and compliance side of Microsoft will use Harvey, and Harvey will widen its own use of Microsoft 365 and Copilot internally. Antony Cook, Microsoft's deputy general counsel, framed it as helping teams work more efficiently and concentrate on complex work. The detail worth noticing is not the endorsement of one product. It is that a company with a capable general assistant of its own, already integrated with the specialist tool, still bought the specialist tool for legal work.
Why a general assistant stops short
A general assistant is built to be useful across every department. It writes email, summarises a meeting, drafts a slide and answers a question about a spreadsheet. That breadth is what makes it good value, and it is also the limit. Legal work carries requirements a general tool does not set out to meet. The source of an authority matters, the version of a clause matters, the line from a document to the advice given matters, and the record of who checked what has to survive scrutiny long after the file closes. A specialist platform is built around those requirements and is designed to show its working.
Why the specialist tool is not the whole answer
Running only the specialist platform carries its own waste. Most of what happens in a firm on any given day is ordinary office work, and paying a legal AI licence to draft a letter to a supplier or tidy a spreadsheet spends money badly. The arrangement Microsoft has settled on, a broad assistant for the general run of work and a specialist platform for the legal work that carries risk, is the one that fits most firms. The two do different jobs and the spending should follow that split.
What this means for a smaller firm
A practice with ten fee earners is not buying at Microsoft's scale, and the lesson is not to copy the products. It is to stop treating this as a single decision with one winner. Work out which of your tasks carry professional risk, which touch confidential client material, and which need an audit trail you would be content to put in front of the SRA or your insurer. Those tasks make the case for a specialist tool, and they are also where economising on the cheaper general assistant tends to cost you. Everything else sits comfortably with the assistant you already pay for.
Before you renew anything, list the work your people put through AI in a normal week and mark the items that involve client data or advice carrying liability. If that marked list is short, the general assistant with a disciplined policy around it will do for now. If it is long, and in most firms it lengthens every month, a specialist tool earns its licence, and you should test it against your own files rather than a demonstration. The decision belongs to the firm rather than the supplier, and the reasons for it belong in writing. A single page naming the tools in use, the work each one handles and the person who approved the split will answer most of what a regulator or an insurer would think to ask.
The announcement is set out in Harvey's note on the expanded collaboration with Microsoft, published on 23 July 2026.
Weighing a legal AI licence against the assistant your firm already pays for is a judgement best made on your own matters, not on a sales deck. That comparison is a short piece of work we do: see how it works.