The use of “on behalf of X” or “on X’s behalf” to mean ‘by X” has long grated on me as, in my head, the phrase is supposed to mean “for X (by someone else)”. I’ve assumed that it is basically a case of speakers selecting “on behalf of” instead of “on the part of”.
Examples from the wild (full context makes the meaning plain):
“This is obviously plagiarism. Obviously, a grievous error on behalf of someone on the Trump campaign. “
“Was that a mistake on behalf of the AFP do you think?”
“ This isn’t just a rush of yuletide generosity on behalf of the trust’s management, it’s all part of the European Working Time Directive, which will apply to junior doctors from August 2004. “
But a little investigation reveals that this is a quite well-established, traditional use of this word.
What are your thoughts?