In brief:
Microsoft Copilot is the AI assistant built into the Microsoft 365 tools your firm already uses: Word, Outlook, Teams and Excel
It is genuinely useful for first drafts, summarising long documents and email threads, and catching up on meetings
It is not a legal research tool, it does not replace professional judgement, and its answers always need checking
Your firm's data stays within your own Microsoft 365 environment and is not used to train Microsoft's AI models
The quality of what Copilot produces depends heavily on the state of your firm's data and permissions, which is where preparation matters
Most law firms we speak to are somewhere between curious and sceptical about AI. Partners have seen the headlines, someone at the firm has quietly tried ChatGPT, and the question keeps coming up in management meetings: should we be doing something with this?
For firms already running on Microsoft 365, the most practical answer usually starts with Copilot, because it sits inside the tools your people use all day rather than being another application to learn. This guide explains what it actually does, where it disappoints, and what to think about before rolling it out. No hype, no scaremongering.
Microsoft Copilot is an AI assistant woven into the Microsoft 365 applications: Word, Outlook, Teams, Excel and PowerPoint. You ask it to do things in plain English, and it works with the content in front of you and, with the right licence, with your firm's wider files, emails and calendars.
That last part is the important distinction. There are two levels:
Copilot Chat is the free version included with Microsoft 365 business plans. It is a secure chat assistant, similar to ChatGPT, but with business-grade data protections applied. It can answer questions, draft text and summarise documents you give it, but it does not automatically know about your firm's files and emails.
Microsoft 365 Copilot is the paid add-on licence, priced per user per month. This is the full experience: Copilot working inside Word, Excel and PowerPoint, and able to draw on your firm's own emails, documents and meetings (only the ones each individual user already has permission to see, which we will come back to).
Worth knowing: Microsoft tightened this up in mid 2026. The in-app Copilot features in Word, Excel and PowerPoint now require the paid licence, where previously some were available more widely. The free Copilot Chat remains available to everyone on a business plan. In practice this means firms can let everyone use the free chat safely while buying full licences only for the people who will get real value from them, which is a sensible way to start.
Copilot in Word will produce a workable first draft from a short instruction, and it can work from your existing documents as a starting point. It will not produce a finished piece of legal drafting, and it should never go out unreviewed, but getting from blank page to reviewable draft in a minute or two is a real time saving on routine correspondence.
Give Copilot a lengthy report, contract or chain of correspondence and ask what it says, what the key dates are, or what obligations it creates. For getting oriented in a matter quickly, this is one of the most immediately useful features, and one of the most popular with fee earners.
Copilot in Outlook summarises long email threads, drafts replies, and helps you find things. Anyone who has returned from a fortnight's leave to a four-figure inbox will understand the appeal.
With recording and transcription switched on, Copilot produces meeting summaries, action lists and answers to questions like "what did we agree about completion dates?" For internal meetings this is quietly transformative: people stop scribbling notes and the record is better. For client calls, your firm needs a policy on recording and consent first.
Copilot in Excel analyses data, builds charts and answers questions about figures in plain English. For practice managers wrestling with billing exports and management reports, this lowers the skill barrier considerably.
An honest list, because this is where expectations most often go wrong.
Copilot does not have access to case law databases, and it is not designed to answer questions of law. Ask it a legal question and it may answer confidently and wrongly. Specialist legal AI tools exist for research; Copilot is a productivity assistant, not counsel.
All AI assistants sometimes produce confident, plausible, incorrect output. Microsoft's own guidance is that Copilot output needs human review, and for a law firm that review is not optional. The working rule we recommend: Copilot produces drafts, humans produce documents.
Copilot draws on your Microsoft 365 environment. It does not automatically see your practice management system, your accounts package or anything else outside Microsoft 365. Connecting those systems is possible where they have modern, accessible interfaces, but it is a separate piece of work, and it is one reason the state of a firm's wider technology matters so much to how useful AI becomes.
This is the one nobody tells you. Copilot's answers are only as good as the files and data it can see. If your document management is chaotic, if old and duplicate versions litter your SharePoint, if permissions were set up years ago and never reviewed, Copilot will faithfully reflect all of that back at you. Microsoft's own security guidance makes the same point: poorly governed and overshared content affects Copilot's results and increases risk. Firms that get the most from Copilot are the ones that sorted their foundations first.
The short answer, for the paid business versions of Copilot, is that the protections are strong and contractual, but they only work as well as your own setup.
What Microsoft commits to, in its published documentation and its Data Protection Addendum with customers:
Prompts and responses stay within the Microsoft 365 service boundary. Your interactions with Copilot are processed under the same security, privacy and compliance commitments as the rest of Microsoft 365, and covered by the same contractual terms.
Your data is not used to train the AI models. Microsoft states plainly that prompts, responses and your business data are not used to train the underlying foundation models.
Copilot respects your existing permissions. It can only surface content the individual user already has permission to access. It also honours sensitivity labels (the classification tags that can restrict what happens to a document) and retention policies.
Interactions are auditable. Administrators can audit Copilot usage through Microsoft's compliance tooling, which matters for firms that need to evidence how client data is handled.
GDPR commitments apply, including Microsoft's EU Data Boundary commitments for data residency.
First, these protections apply to the business versions of Copilot signed into a work account. They do not apply to consumer AI tools, which is why the quiet use of personal ChatGPT accounts around your firm is a far bigger risk than a properly governed Copilot rollout. If people are going to use AI anyway, and they are, giving them a safe version is the defensive move.
Second, "Copilot respects your permissions" cuts both ways. If your permissions are wrong, Copilot makes the consequences visible. A folder accidentally shared with the whole firm was always a problem; Copilot just makes it easier for someone to stumble across it. This is why a permissions review belongs before rollout, not after.
Who actually needs the paid licence? Start with a pilot group who live in documents and email, learn from them, then expand. Everyone else can use the free Copilot Chat safely in the meantime
When did anyone last review your permissions and sharing? If the answer is "not recently", do that first.
What is your policy on AI use? A short, clear internal policy on what Copilot may and may not be used for, and the review standard for its output, is worth writing before day one. Your compliance officer should be part of that conversation, particularly around client confidentiality and engagement terms.
What about recording client calls? Teams meeting summaries need recording and transcription. Decide your consent approach before fee earners discover the feature themselves.
How will you know if it is working? Decide what success looks like (time saved on routine drafting, faster matter onboarding, fewer hours lost to email) so the rollout can be judged on evidence rather than vibes.
Copilot is neither the revolution the headlines promise nor a gimmick to ignore. For a law firm on Microsoft 365 it is a genuinely useful assistant for drafting, summarising and catching up, with strong contractual data protections, and a licensing model that lets you start small.
The firms seeing real benefit share one trait: their foundations were in order first. Clean data, sensible permissions, a modern Microsoft 365 setup and a clear policy. The firms that switch it on over the top of years of accumulated mess get mediocre results and conclude AI is overrated. The tool is the same; the preparation is the difference.
That preparation is exactly the work we help law firms do. If your firm is weighing up Copilot and wants a straight answer on whether you are ready for it, we are happy to have that conversation.
Want the bigger picture first? Our Legal Modern Workplace whitepaper sets out how the pieces fit together: practice management, Microsoft 365, security and AI. [Download the whitepaper] or [get in touch] to talk it through.
Partly. Copilot Chat, the secure chat assistant, is included with Microsoft 365 business plans at no extra cost. The full Microsoft 365 Copilot experience inside Word, Excel and PowerPoint, drawing on your firm's own content, is a paid per-user add-on licence.
No. Microsoft states in its documentation and contractual terms that prompts, responses and business data from Microsoft 365 Copilot are not used to train its foundation AI models.
No. Copilot can only access content that the individual user already has permission to see. That protection is only as good as your permissions setup, which is why a review of sharing and access is a sensible first step before rollout.
No. Copilot has no access to legal databases and is not designed to answer questions of law. It is a productivity assistant for drafting, summarising and analysis. Specialist tools exist for legal research, and all AI output should be reviewed by a qualified person regardless.
Review permissions and sharing across Microsoft 365, agree a short internal AI use policy with your compliance officer, decide your approach to meeting recording, pick a pilot group for paid licences, and define what success would look like.
Sources: Microsoft Learn, "Data, Privacy, and Security for Microsoft 365 Copilot"; Microsoft Learn, "Enterprise data protection in Microsoft 365 Copilot and Microsoft 365 Copilot Chat"; Microsoft Learn, "Security for Microsoft 365 Copilot"; Microsoft 365 Copilot product documentation. All accessed July 2026.
nexian.co.uk/legal-modern-workplace-whitepaper
Or get in touch with the team if you would like to talk through where your firm is on its technology journey.