When to use who, whom

In reply to a reader on when to use “whom” and “who”, the relevant column of a newspaper quoted as one of the examples as follows:-

“The girl who she trusted has let her down.” (“who” is a relative pronoun used as the object of the clause “who she trusted”)
In a more formal style, the above sentence would be written “The girl whom she trusted has let her down.”

The above example appears to suggest that both “whom” and “who” can be used in the given sentence except that the use of the former is in a more formal style. I find this confusing and has written an e-mail to the editor who has accordingly published it in the newspaper:-

Friday September 18, 2009
When to use who, whom
OPEN CHANNEL

I REFER to the answer given to Cece (Mind Our English, Aug 27) on the use of who/whom.

The use of “who” or “whom” has confused many including experienced writers who often go wrong if they are not vigilant enough. Perhaps, some writers indulge in informal usages, sometimes, for being natural or for fluency.

In the reference book contributed/edited by 12 experts on English (many of whom are PhD holders) and published by Reader’s Digest guiding readers to speak and write better, it says that “who” or “whom” and “whoever” or “whomever” often cause difficulties and that in practice, “who” is widely used in both roles (subject and object), especially in speech; “whom” is regarded as rather formal. It does, however, show the correct usages of “who” and “whom”.

In the sentence, “The girl who she trusted has let her down” (which is quite similar to a sentence quoted in the reference book showing “who” is the only correct form to be used), it could lead readers to analyse and treat “she trusted” to be a parenthetical clause/parenthesis. The sentence would then be incomplete.

In fact, MOE published an article on the subject by Oh Teik Theam on Sept 29, 2006 in which the writer had given very good advice about the correct usage.

Such advice which can be an easy guide is reproduced herein:-

“To decide when to use ‘who’ or ‘whom’, apply this test: if the thought in the who/whom clause is best expressed by he/she/they, use ‘who’; if him/her/them does the trick, use ‘whom’.”

Perhaps, if we do not concern ourselves so much with the informal usage, the confusion will be greatly reduced, if not eliminated. – Kengt, Penang