Amos said:

One does not "write for who".

Many of us (including me) tend to glaze over when given the technical grammatical reasons for approved usages. I flatter myself that I can write well and write grammatically, but somehow my English teachers never made most of the terminology relevant or meaningful.

There are simple procedures, though, that accomplish the same (and correct) result, without resorting to grammar jargon.

In the case of who/whom, the decision of which to use is always solved by retaining the sentence structure but substituting "he" or "him" ("she" or "her").

In Amos's example above, "One does not write for he" is immediately recognizable as wrong. It has to be recast as "One does not write for him." Thus, "write for whom" is indicated.

I have never seen this test fail to indicate the right usage.

Dave Oesterreich