A reader asks,
Is there a difference in the use of these two prepositional phrases? I get mixed up a lot of times. I’d appreciate your clarifying this in one of your posts.
“On behalf of” means, “as representing,” and “in behalf of” means “for the advantage of.” People or agencies who act as representatives of others, act “on behalf of”:
The ACLU brought suit against the city on behalf of three residents.
People whose intention is merely to be helpful act “in behalf of”:
The residents along the border collected food in behalf of the migrants.
Merriam-Webster does not draw a distinction between the phrases, but includes both in its entry for behalf:
“in behalf of or on behalf of preposition: in the interest of, as the representative of, for the benefit of. Ex. “This letter is written in behalf of my client.”
The OED, on the other hand, deplores such a merger of meaning:
In recent use we often find on behalf in the sense of in behalf, to the loss of an important distinction.
According to the OED, on behalf of means, “on the part of (another),” with the notion of official agency; in behalf of means, “in the interest of, as a friend or defender of, for the benefit of.” The connotation is the notion of interposition.
The Chicago Manual of Style supports the distinction for American speakers in its “Good Usage versus common usage” section:
In behalf of means “in the interest or for the benefit of.” Ex. “The decision is in behalf of the patient.” On behalf of means “acting as agent or representative of.” Ex. “On behalf of Mr. Scott, I would like to express heartfelt thanks.”