Who and Whom

This one opens a big can of worms. "Who" is a subjective — or nominative — pronoun, along with "he," "she," "it," "we," and "they." It's used when the pronoun acts as the subject of a clause. "Whom" is an objective pronoun, along with "him," "her," "it", "us," and "them." It's used when the pronoun acts as the object of a clause. Using "who" or "whom" depends on whether you're referring to the subject or object of a sentence. When in doubt, substitute "who" with the subjective pronouns "he" or "she," e.g., Who loves you? cf., He loves me.Similarly, you can also substitute "whom" with the objective pronouns "him" or "her." e.g., I consulted an attorney whom I met in New York. cf., I consulted him.