The smallest amount of time a lawyer can bill you for is six minutes, and one person decided that. Reginald Heber Smith ran Hale and Dorr in Boston. Around 1920 he had his lawyers keep timesheets. Not to bill anyone. He wanted to know where the firm's capacity was going, which matters made money, and who was actually pulling weight.
He later said his “only contribution” was deciding that the minimum entry should be one-tenth of an hour. Six minutes. Not because six minutes is a natural unit of legal thought, but because tenths divide cleanly, and a clerk adding up a month of them by hand should not have to do fractions.
For thirty years it was a management tool
This is the part that gets lost. Smith built a measurement system for internal use, and it worked. It told him which practice areas were profitable, where the leverage was, and which clients were quietly subsidized by everyone else. He wrote the method up so other firms could copy it, and it spread through the profession as office-management doctrine rather than as a pricing scheme.
Hourly rates existed alongside it, but the dominant way to price legal work in the first half of the century was closer to judgment: what the matter was worth, what the client could bear, what the local bar's minimum-fee schedule said. The timesheet was how the firm understood itself, not how it billed.
Then the measurement became the product
The 1950s and 60s changed what the clock was for. Rate pressure, growing corporate clients who wanted itemization, and a profession newly anxious about its own economics turned the internal record into the invoice. A 1958 report widely credited with accelerating the shift suggested that a reasonable annual target was around 1,300 billable hours.
Once your time is the product, an entire set of incentives flips at once. Effort becomes revenue. Duplication becomes revenue. And speed, the thing every client wants and every firm advertises, becomes a cost you absorb yourself.
The grid nobody designed on purpose
Smith's clerical convenience is now the resolution at which the entire profession perceives work. Every task rounds to the nearest tenth, which means a two-minute call and a six-minute call are the same event as far as the ledger is concerned.
- 1–6 min0.1
- 7–12 min0.2
- 13–18 min0.3
- 19–24 min0.4
- 25–30 min0.5
- 31–36 min0.6
- 37–42 min0.7
- 43–48 min0.8
- 49–54 min0.9
- 55–60 min1.0
The practical effect is a floor under small work. It also means the firm's most granular view of its own operations is six minutes wide, which is far too coarse to see the thing that actually costs money: the non-billable operational work surrounding every matter, which no one records at all.
The profession said this out loud in 2002
None of this is a secret critique from outside. The ABA's own Commission on Billable Hours, reporting in 2002, wrote that the model penalizes the efficient and productive lawyer. That is the governing body of the profession stating that its dominant pricing mechanism rewards slowness, and then the profession kept using it for another two decades.
The reason it survived is not stupidity. It is that the hourly model solves a real problem elegantly: it allocates risk to the client and requires the firm to know almost nothing about its own cost to deliver. Fixed pricing requires the opposite. You cannot quote a number for a matter until you know what that matter actually costs you to run, and most firms have never measured the part that is not billable.
Which is why AI makes this urgent instead of interesting
The contradiction has been livable for seventy years because the work could only compress so far. That constraint is going away. When a firm can genuinely produce the same answer in a fraction of the time, the hourly model turns its best capability into a revenue cut, and clients who can see the compression will not keep paying for the old duration.
Two firms reach the same answer. The one that took longer bills more, and nobody in the room blinks. That has always been the strange part. It stops being sustainable the moment the gap between the two firms gets wide enough for the client to notice.
The way out is not to slow down or to abandon the hour overnight. It is to know your cost to deliver a matter well enough that price can be set on scope. That is an operations project before it is a pricing decision, and it starts with measuring the work Smith's timesheet was never pointed at.
If you want the mechanics rather than the history, our guide to billable hours covers increments, targets, realization, and a calculator for what the gaps cost.
The rest of the series
Four times a profession ran out of people to absorb its own routine work, and what actually ended each one.
- IBM Exists Because the Census Could Not Finish Counting. The 1880 census took until 1887 to tabulate by hand. The machine built to clear that backlog became the computer industry.
- The Year the Stock Exchange Closed on Wednesdays. For most of 1968 the busiest market on earth shut one day a week because the back office could not clear the paper.
- The Paralegal Was Invented to Make Legal Services Cheaper. A 1968 ABA resolution created a role to absorb a lawyer's tedious and routine detail. The role became billable.