- Speaking or acting for.
- On behalf of all those present, may I thank you for a well executed presentation.
Although on behalf of and in behalf of are usually used interchangeably, with the former steadily replacing the latter in frequency of use, a distinction in meaning has been made by some commentators. As those commentators have it:
- to "speak on behalf of a person or entity" is to "speak on their side or part as their explicitly or implicitly delegated representative."
- On behalf of the mayor, I declare this to be our city's fix-up and paint-up day.
- To "speak in behalf of a person or entity" is to "speak in their interest, favor, or aid, without explicit deputization, and especially if they are unable to speak for themselves."
- to plead in behalf of a cause.
Historically, in was formerly much more common (7:1) in US usage than on with behalf. It has been almost totally (30:1) replaced by on. Moreover the remaining usage of in behalf of does not systematically follow the pattern prescribed by the commentators. Current British usage also shows on behalf of to be much more common than in behalf of. Garner's Modern American Usage (2009) suggests that interchangeability is almost completely accepted.