Style manuals decree writers must hyphenate most phrasal adjectives when they precede the noun the phrase modifies, but many lawyers don't know the rule; many who know reject it. (See Shannon's comment.) An example of a controversial phrasal adjective occurs at the end of the third paragraph:
requires time-consuming semantic processing.
Some lawyers say the phrase needs no hyphen because time is a noun, and one would never think it modifies processing; but a writer who guesses what "no one" thinks exceeds his expertise. Time may usually be a noun, but in time-consuming, time functions as an adverb. In my example the hyphen avoids a different ambiguity that time is the object of requires: requires time...to consume semantic processing.
Bryan Garner and Wayne Schiess agree that with the standard exceptions phrasal adjectives should be hyphenated, but Sasha Volokh argues for punctuating only as necessary to avoid probable ambiguity, not a hypothetical one. I disagree with the three authorities. Garner and Schiess give insufficient weight to the opinions of some competent legal writers who often omit hyphens, and Garner and Schiess don't identify unneeded punctuation as redundancy. Volokh qualifies the hyphen rule but on the wrong basis. Volokh thinks that the hyphen wastes white space when the adverb can't plausibly be an adjective modifying a subsequent noun, but miscue isn't the only problem with omitting hyphens; the more common problem is delay. Omitting the hyphen delays informing the reader of what the adverb modifies until the reader reaches the noun. Then the reader's brain must engage in time-consuming semantic processing before concluding whether time modifies consuming or a subsequent word. In the example the reader must reach beyond semantic to processing before parsing the phrase.
Against Volokh's commonly encountered position that writers should omit hyphens when miscue is improbable, what allows omitting the hyphen isn't that the adverb can't plausibly be an adjective but that it very plausibly is an adverb, creating a self-contained phrase, such as high-school student. Even a self-contained phrase isn't usually enough to warrant omitting the hyphen. Most self-contained phrases should be hyphenated because the stock meaning won't necessarily be salient for all readers; a high school student could be a college student on drugs. The set of self-contained professional phrases, terms of art, such as summary judgment motion or municipal code violation, are the true exceptions to the phrasal-adjective rule, not only because of audience uniformity. When one of these phrases occurs in a document, repetitions often abound, so once a summary judgment motion features in a case the writer will probably mention it again. Repetition compounds the redundancy of hyphens and adds disproportionate clutter.
Do professional writers who obey the Chicago Manual of Style or similar guides know how to edit law documents better than professional legal writers? The style guides envision writing to a broader audience. Despite some plain-language advocates' exaggeration of the similarities, writing for lawyers sometimes differs from writing for educated nonprofessionals.