Can a law firm bill a client for time AI saved?

The rule being applied is the ordinary one about reasonable fees, and nothing about the technology changes it. A lawyer billing by the hour is billing for hours, and an hour that was not worked is not billable however much value the work carried. The American Bar Association's Standing Committee on Ethics and Professional Responsibility said this directly in Formal Opinion 512, issued in 2024, and the reason it needed saying is that the alternative is genuinely tempting: the work is the same work, the client's problem is the same problem, and only the duration moved.

Two related charges are more commonly attempted and both fail on the same reasoning. Time spent learning a tool is not client work, so it is general overhead and stays with the firm, unless a particular client asked for a particular tool on a particular matter. And the subscription itself is a cost of doing business by default; it becomes a chargeable disbursement only where the client agreed to that in advance, in terms specific enough that the client knew what was being agreed.

The consequence firms notice second is that an hourly rate becomes an actively bad instrument for AI-assisted work. If the tool halves the time on a category of matter, the firm's revenue on that category halves too, and the only lawful ways to recover it are to raise the rate, to change the pricing basis, or to do more matters. That is a commercial decision to make deliberately, in advance, rather than discover through a slow decline in realisation on a practice area nobody thought had changed.

Fixed and capped fees behave in the opposite direction, which is why the question tends to arrive from firms that bill hourly and not from firms that do not. Under a fixed fee the client bought an outcome and the efficiency accrues to whoever bore the risk of it taking longer, which was the firm. That is not a way around the rule; it is a different bargain, struck before the work rather than discovered after it.

The record-keeping question is smaller than it looks and worth settling once. Nothing requires a firm to itemise which minutes were AI-assisted, because the entry is a statement about time spent, not about method. What does require care is the entry that describes work in a way the time no longer supports — an eight-hour narrative attached to a two-hour entry invites exactly the enquiry a firm least wants, and the narrative is the part that has to be rewritten.

Where a client has been told a tool will be used and has agreed to it, the useful conversation is about the pricing basis rather than the disclosure. Clients who are told that a review that used to take a week now takes a day are rarely surprised by a proposal to price the day; they are surprised by an invoice that says a week.