90% of UK Lawyers Now Use AI, and the Billable Hour Is Starting to Crack

The billable hour survived the fax machine, the internet and the smartphone. AI is a different kind of threat. According to legal software company Clio's UK and Ireland Legal Insights Report 2026, nearly 90% of legal professionals in the UK and Ireland now use AI, and the practice of charging clients by the hour for work that software can do in seconds is coming under direct pressure.

The productivity numbers explain why. Among firms using AI, almost 80% told Clio they can handle more work without increasing resources, and over 70% said AI cut costs by absorbing administrative work once done by support staff. About one in five firms that have widely adopted AI already report difficulty meeting billable-hour targets.

You cannot charge 16 hours for something that takes 16 seconds, Nick Rowles-Davies, founder and CEO of legal finance fund Lexolent, told CNBC. Routine document work is the most exposed, he said, though complex legal judgment still requires humans, particularly when interpreting AI output and setting strategy. Lawyers also need to catch hallucinations, an area where courts have sanctioned attorneys for filing briefs citing cases that do not exist.

The market is pricing in the shift. A Deloitte survey expects the share of legal work charged by the hour to fall from 72% to 44% over the next two to three years. The UK's biggest firms are already restructuring around the technology: A&O Shearman worked with legal AI company Harvey to build agents that review loan agreements and analyze regulatory filings in minutes rather than hours, and Slaughter and May has rolled Harvey out across all practice areas this year.

The deeper disruption is in how lawyers learn the trade. Reviewing hundreds of documents, drafting contracts and researching cases traditionally taught junior associates the building blocks of law, as Teesside University professor Mansoor Soomro noted to CNBC. As AI absorbs that grunt work, firms must deliberately replace the learning it provided. A faster route to a draft does not automatically mean a faster route to competence, said Jorge Bestard, head of EMEA at Harvey.

A&O Shearman says it now weighs curiosity and entrepreneurship more heavily in talent decisions and is building career paths in legal engineering and AI delivery that barely existed a few years ago, according to Francesca Bennetts, the firm's head of legal talent in London. The billable hour will not vanish overnight, but the economics that sustained it are visibly shifting. The lawyers who thrive will be the ones who know how to connect multiple domains and challenge what the machine produces, not the ones who can produce the most of it.

There is also a human question hiding in the efficiency math. Clio's report found 51% of legal professionals work evenings but only 32% want to, and 22% work weekends versus 11% who would choose to. Whether AI makes lawyers' lives better depends on what firms do with the recovered hours. If the gains flow only to partner margins, the profession will have automated the work without improving the job.