Recently, I recommended using on instead of upon in your writing because on is the common word, and upon is the formal word that means the same thing:
Using upon or on depends on the context. If you want or need to sound more formal (or, as Follett says, “bookish”) use upon. It also is acceptable to use upon when the sense in which it is used is “on the occasion of” or “when (something) occurs.” . . . Otherwise, use on in all other cases because it will help you achieve a more conversational tone.
Here, I discuss another subtle word choice that, if used correctly, will establish your bona fides as a precise legal writer—the difference between part and portion.
Have you ever read something like the following sentence in a brief? “In 2010, the court found unconstitutional the portion of the [statute/law/rule] that . . . .” The focus here is on the word portion. Is portion used correctly in the sentence? The answer is no. But does it really matter? It does, for the precise legal writer.
Garner’s Modern American Usage correctly points out that “[t]here are connotative differences” between portion and part. Portion generally means “share,” or “an entity cut (or as if cut) away from the whole.” Part, however, means “a constituent piece of the whole.”
Longman Guide to English Usage makes the same distinction: “A portion is a share, such as a helping of food, allotted to someone. A part is a limited quantity taken from a whole, and this is the more general word.”
H.W. Fowler’s A Dictionary of Modern English Usage (First Edition), calls portion a “formal” or “outdoor” word, and that the “indoor” or “common” word part is preferred. Not one to mince words, Fowler calls portion a favorite “piece of buckram.” (Ed: buckram is defined in one sense as a stiffness of manner, or extreme preciseness or formality). Fowler adds: “Few things contribute more to vigour of style than a practical realization that the . . . dominant or proper or vernacular or current names, are better than . . . formal words” like portion.
Substituting the common word part for the formal word portion is consistent with the purpose of this website, namely, to achieve a plainer, more conversational tone in your writing. So you should use part in most contexts.
But as Garner advises above, there are certain contexts where portion is the correct word to use. You wouldn’t say, for example: “I would like a part of the Thanksgiving turkey to take home as leftovers.” You, of course, ordinarily would say: “I would like a portion of the turkey to take home as leftovers.” So don’t necessarily relegate portion to the usage-wastebasket.
As a general rule, then, you should ask yourself the following questions when deciding whether to use portion or part: Am I referring to a portion of food, or some other thing that’s being cut away from the whole? Or am I referring to something that is a constituent piece of something larger, or that comprises a constituent piece of the whole? (part) If you have any doubt, use the default common word part.
But you never should use portion when referring in a brief to part of a statute, rule, law, or case. If you do, it might result in your judge thinking about what’s for dinner, instead of the merits of your client’s case.