Measuring What Matters: A Practical Framework for Legal AI ROI
How law firms are connecting AI adoption to growth, margins, and output per lawyer, with insights from the Briefing AI Leaders Community Index.
Legal AI adoption across law firms has entered a new phase.
The question is no longer whether firms should be investing in AI, but how they define success — and whether legal helps firms grow revenue, protect margins, and increase output per lawyer in a more competitive market.
Recent findings from the Briefing AI Leaders Community Index offer a useful snapshot of where the market is today. Surveying more than 70 senior leaders responsible for AI strategy and deployment at leading UK law firms, the research captures a profession moving beyond experimentation and into early operational use.
What the data makes clear is that adoption is accelerating. What’s evolving is the conversation around impact.
What the AI Leaders Index Tells us About the Market
The Briefing research reflects a broad cross-section of law firms at different stages of their AI journey, using different tools and operating under different commercial pressures. Taken together, the findings highlight a shared direction of travel.
Half of surveyed firms (50%) have already procured domain-specific legal AI tools, and another 33% are in the purchase process or trialing. AI capability is quickly becoming part of the modern law firm toolkit.
At the same time, the research underscores a shift in expectations. Firm leaders increasingly view AI not just as an efficiency play, but as a lever for improving quality, responsiveness, and lawyer experience. Clients, too, are asking more pointed questions about how firms use AI — particularly in relation to cost, speed, and risk.
In other words, AI is moving from novelty to normal. And with that shift comes a higher bar for how value is articulated.
From Activity to Outcomes
What the AI Leaders Index surfaces isn’t uncertainty about AI’s potential. It’s the reality that measuring value in a legal context is nuanced, particularly as firms face increasing client pressure on pricing, turnaround times, and demonstrable value.
In fact, 82% of AI leaders surveyed say that assessing ROI remains a significant hurdle to wider adoption. Time saved only matters insofar as it translates into better client service, stronger margins, improved utilization, or more meaningful work for lawyers.
ROI, in other words, is contextual.
Looking ahead, 79% of leaders surveyed anticipate lawyers taking a more active role in client management and cross-selling — supported by AI-driven efficiencies. That makes the ability to connect AI usage to tangible business outcomes even more important.
This is where firms are increasingly focusing: not just on whether AI is being used, but on how its impact shows up in real workflows, matters, and firm-level results.
Harvey’s Perspective on Legal AI ROI
This is the lens behind The Legal AI ROI Guide for Law Firms.
The guide is designed to help firms connect AI usage to the metrics leadership actually cares about — growth, profitability, and the ability to scale without linear headcount increases. It draws on Harvey customer data and case studies to show how firms are already translating AI adoption into measurable business impact.
Across surveyed Harvey users, typical lawyers report saving 15–25 hours per month, with power users saving 30–50+ hours. More importantly, the guide shows how firms connect those time savings to outcomes leadership actually cares about: faster RFP responses, improved leverage on fixed-fee work, increased matter capacity, and better lawyer experience.
Examples from the guide show how firms are already translating AI adoption into commercial impact, including firms that have:
- Responded to urgent client requests in under 48 hours and won new business
- Reduced due diligence review time by 50%
- Increased case capacity by more than 30%
- Achieved efficiency improvements of up to 90% in document-heavy workflows
These outcomes don’t come from AI alone. They come from pairing the technology with clear use cases, thoughtful rollout, and from firms using AI to increase throughput, improve leverage, and compete more effectively for new work.
Defining the Next Phase of Legal AI
The Briefing AI Leaders Community Index shows a market in motion. Firms are investing, experimenting, and learning quickly. The next phase is about making impact felt, both internally and externally.
If you’re thinking about how to define and communicate ROI for your firm, the Legal AI ROI Guide offers a practical place to start.
Upcoming research with RSGI will build on this foundation, examining how leading firms are going further, using Harvey not just to improve efficiency, but to rethink delivery models and create new sources of value.
