New research reveals that legal and governance departments are outpacing every other corporate function in artificial intelligence adoption across enterprise businesses.
Harmonic Security, which sells AI governance software, analysed 1,935,247 classified AI-session minutes across its enterprise client base and broke the results down by department.
Legal and governance finished first, accounting for 19.5 percent of all AI hours logged across the organisations studied in the dataset.
Go to Market functions, covering sales, marketing, and business development, came in second at 17.7 percent, with design and development taking third place at 13.3 percent.
The financial pressures facing in-house legal teams likely explain much of this behaviour, as in-house lawyers have no structural incentive to resist efficiency in the way private practice lawyers do.
Every hour a legal department saves is an hour it does not have to purchase from outside counsel at rates that can reach thousands of pounds per hour.
There is no billable target to hit and no realization rate to protect, meaning an in-house lawyer’s professional incentives align directly with the core promise of artificial intelligence tools.
The Harbor/CLOC law department survey previously found general counsels projecting less outside counsel spend and actively using AI as leverage in fee negotiations with law firms.
Harmonic’s new report converts those earlier projections into concrete, measured behaviour, showing that in-house teams have moved well beyond theoretical enthusiasm for the technology.
The study also found that legal departments run 67 percent of their AI hours through ChatGPT, which Harmonic identifies as the largest single function-tool concentration anywhere in the entire dataset.
Claude accounts for 18 percent of legal AI usage, with Copilot taking 9 percent, Gemini 4 percent, and Perplexity just 1 percent, though the data is several months old.
The report notes that “Claude’s profile is different — it handles 41% of Strategy work and 40% of Finance, reflecting its stronger position in tasks requiring sustained analytical reasoning.”
Legal departments also emerged as the best-behaved function in the study, with only 4 percent of AI time running through free personal accounts rather than approved enterprise platforms.
All told, legal accounts for roughly a third of all enterprise-plan AI hours, a striking concentration for a single corporate function.
Harmonic CEO Alastair Paterson offered a measured assessment of the findings, stating: “Legal is to be commended for largely using enterprise-tools but even the small amount of personal use we identified is a risk.”
Meanwhile, separate data from 8am found small law firms are actually billing more hours per case than before AI arrived, raising questions about whether the technology is always driving genuine efficiency gains.
The contrasting picture between in-house teams and private practice suggests AI may be creating more capacity for legal work rather than simply making existing work faster to complete.