UK's biggest law firms race to lead AI adoption
Date: 22 September 2025
AI is now a visible differentiator in the UK legal market. New research from Thomson Reuters shows top firms promoting, staffing, and training around AI at a faster clip-while strategy still lags for many.
The headline numbers
- 78% of the top 40 UK firms publicly advertise AI use (up from 60%).
- Among the top 20, firms with a Head of AI rose from 35% to 45% in a year.
- 75%+ of the top 20 now have in-house AI transformation teams (up from 60%). Only 35% of firms ranked 21-40 have a dedicated AI department.
- Just 24% of UK firms have an AI adoption strategy. 43% are adopting AI without one.
- 55% of the top 20 offer AI training for staff (up from 20%); only 10% of firms ranked 21-40 do the same.
Raghu Ramanathan, president of legal professionals at Thomson Reuters, said: 'An increasing number of law firm customers recognise AI's potential to enhance both productivity and client service.'
He added that the largest firms are moving faster, creating a gap smaller firms will want to close: 'The UK's very largest law firms are responding to this pressure to adopt and integrate AI tools - but the next tier of law firms appears to be adapting more slowly.'
Why this matters for client panels
Panel decisions are shifting toward measurable AI capability and outcomes. Buyers will ask how you use AI to deliver speed, accuracy, and cost control-without compromising confidentiality or ethics.
As Ramanathan notes, clients expect firms to deploy GenAI responsibly and use top-shelf professional-grade tools. Firms that can prove that with evidence, not slides, will gain ground.
Where leaders are pulling ahead
- Clear ownership: Appointed Heads of AI with budget and delivery mandate.
- Dedicated teams: Cross-functional squads across legal ops, KM, IT, risk, and practice groups.
- Training at scale: Role-based curricula for partners, associates, PSLs, and support teams.
- Public proof: Case studies and service descriptions that show real outcomes.
The risk: adoption without strategy
Adopting tools without a plan exposes firms to inconsistent quality, unmanaged confidentiality risk, and weak client narratives. It also leads to duplicated spend and shadow tooling.
A concise, firm-wide strategy aligns use cases, governance, training, procurement, pricing, and measurement-so pilots turn into repeatable delivery.
What leaders should do now
- Set a 90-day AI plan: Define top use cases by practice (e.g., research, drafting, due diligence, investigations, eDiscovery).
- Appoint accountable ownership: Name a Head of AI and a cross-practice steering group.
- Establish guardrails: Confidentiality, privilege, client consent, model selection, and approval flows.
- Run focused pilots: 3-5 workflows with clear metrics (time saved, accuracy, recovery, client impact).
- Upgrade training: Mandatory baseline + role-specific playbooks and matter templates.
- Evidence for clients: Create short, verifiable summaries of outcomes, QA steps, and tooling.
- Commercial model: Align pricing and AFAs to capture efficiency and maintain margin.
- Vendor standards: Security reviews, data handling, audit, uptime, and support expectations.
What clients should ask panel firms
- Which AI use cases are live today, and how do you validate accuracy?
- How do you protect privileged and client-confidential data?
- What training do fee-earners receive, and how is performance measured?
- Which models and vendors do you use, and why are they appropriate for legal work?
- Show recent matters where AI improved turnaround or cost-what was the audit trail?
Training that moves the needle
Firms that scale skills win. Build curricula that map to daily workflows, templates, and matter types-not generic demos. For role-based courses and certifications by job function, see Complete AI Training: Courses by Job.
Bottom line
AI is now a selection criterion, not a side project. The top firms are pairing visible capability with training and leadership. The rest can close the gap quickly-if they move with a clear plan, tight governance, and proof clients can trust.
Your membership also unlocks:
