The man on the Clapham omnibus

omnibus (TRANSPORT) Show phonetics
noun [C] OLD USE
a bus
the man/woman on the Clapham omnibus UK OLD-FASHIONED
an imaginary person whose opinions or ideas are considered to be typical of those of ordinary British people:
The man on the Clapham omnibus probably knows nothing about Rwanda.

The man on the Clapham omnibus is a descriptive formulation of a reasonably educated and intelligent but non-specialist person — a reasonable man, a hypothetical person against whom a defendant's conduct might be judged in an English law civil action for negligence. This standard of care comparable to that which might be exercised by "the man on the Clapham omnibus" was first mentioned by Greer LJ in Hall v. Brooklands Auto-Racing Club (1933) 1 KB 205.

The first reported legal quotation of the phrase is in the case of McQuire v. Western Morning News^[1] a libel case, in which Sir Richard Henn Collins MR attributes it to Lord Bowen, who had died nine years earlier.

It is derived from the phrase the bald-headed man at the back of the Clapham omnibus, coined by the 19th century journalist Walter Bagehot to describe the normal man of London, so used because Clapham in south London at the time was a non-descript commuter suburb and was seen to represent "ordinary" London. Omnibus is a now archaic expression for a public bus, but would have been common usage amongst the judiciary at the beginning of the 20th century.

This expression has also been incorporated in Canadian patent jurisprudence, notably Beloit v. Valmet OY (1986), C.P.R. (3d) 289^[2] in its eloquent discussion regarding the test for obviousness.

In Australia, the "Clapham omnibus" expression inspired a local equivalent, "the hypothetical person on a hypothetical Bondi tram"^[3]

References

1. ^ [1903] 2 KB 100 (CA) at 109 per Collins MR
2. ^ The Beloit-Valmet saga continues
3. ^ Papatonakis v Australian Telecommunications Commission (1985) 156 CLR 7 at 36 per Deane J