where. Part A: For “in which.” In formal prose, “where” should not be used as a relative pronoun instead of as a locative — thus, not *”case where” but “case in which.” But if you want a relaxed tone, “where” may be more suitable. In the following example, the contraction “I’ve” might not comfortably fit in the same sentence as “in which” — hence “where” is justifiable: “I’ve deliberately chosen an example where this unspeakable cluster did not stand out.” Richard A. Lanham, Revising Prose 29 (1979). Part B: For “when.” Sometimes the locative “where” is misused for the temporal “when” — e.g.: “If ever there was a year where [read ‘when’] athletes burned and raged at close of day, it was this one.” David Steele, “Aging with Grace, Success,” S.F. Chron., 24 Dec. 2001, at C1. *Invariably inferior form. For information about the Language-Change Index click here. ——————– Quotation of the Day: “The writer must take his stand and support it to the best of his ability, but he does not do this effectively by acting as if no other opinions were possible. . . . The good writer of argumentation, therefore, must use the debater’s technique of preparing both — or all — sides. Since argumentation is one-sided only in purpose, perhaps it would be better to say it is one-directional.” John E. Jordan, Using Rhetoric 66 (1965).