Part of the answer to why lawyers don't perform various writing tasks correctly is that many don't know how. Hyphenating phrasal adjectives? How many lawyers can identify one? So norms develop that hyphenation doesn't look right. Understanding phrasal adjectives isn't vital, but to know if your ghostwriter punctuates correctly, you must understand the distinction between restrictive and nonrestrictive modifiers. Grammar textbooks emphasize applying the distinction when the modifier is a clause starting with a relative pronoun, such as who, which, or that. Adverbial clauses, starting with words like when, since, because, if, are harder, and their difficulty may be the reason the textbooks apply the distinction to adverbs less often. The rule is the same whether the modifier is adjectival or adverbial: restrictive clauses are not set off by commas, whereas descriptive clauses are. A major exception is that longer initial clauses and phrases are set off, even if restrictive.
I'm going to discuss some of the harder-to-classify adverbial clauses. The pedagogical principle is that the basis for categories becomes clearest at their edges. I don't know that every authority assents to my classification, but if you attend to my logic you will grasp the distinction between restrictive and nonrestrictive (sometimes called descriptive) modifiers, and you can then judge whether your ghostwriter gets it right most of the time.
The test is: does the modifier make the set of objects or actions that satisfy the modified term a proper subset — a subpart — of the set of objects or actions that satisfy the unmodified term?
The miners who worked beneath the surface died in the accident.An easy adjectival example to start, the unpunctuated clause beginning with who is restrictive. The only miners who died in the accident were the ones who worked beneath the surface; some didn't die.
The miners, who worked beneath the surface, died in the accident.The same phrase becomes nonrestrictive. You start with miners and don't reduce the number of them who died by another criterion: whether they worked beneath the surface. You are talking about all the miners, not a proper subset, and offering further description of them without limiting the number being considered.
Now let's look at some adverbial clauses, which are harder and will cement the distinction. The first one starts with because.
The miners died because their employer cut spending on safety measures.The adverbial clause beginning with because modifies died. Does it restrict or merely describe the meaning of died? It restricts it because the statement limits the deaths that make the sentence true to those caused by the employer's cut in safety spending. If the miners died but their deaths had nothing to do with decreased safety spending, the sentence becomes false. Clauses beginning with because aren't usually preceded by commas because they are restrictive adverbial clauses.
Consider an adverb with much the same meaning in one of its senses as because, since. This one is very hard. Take the same sentence, replacing because with since:
The miners died, since their employer cut spending on safety measures.Although this sense of since means much the same as because, it differs subtly. If the miners died for a different reason, denial of the because sentence speaks truth. If the miners died because the country was at war and the enemy bombed the mines, then the correct answer to "Did the miners die because of withheld safety spending?" is no, but what is the answer to: "Did the miners die, since their employer underspent on safety"? The since clause doesn't state a restriction on the acts of dying that count for the sentence's truth. Merriam Webster's supplies because as a synonym for since but defines the relevant sense as "in view of the fact that," whereas it defines because as "for the reason that." The assertion that the miners died because... imparts the reason for their death and is false if the reason is wrong. The assertion that the miners died since ... asserts a background fact that is a presumption underlying the sentence's utterance. If someone asks "Did the miners die, since the employer spent too little on safety" when employer underspending wasn't the reason, the question should elicit denial only of the since clause, not the whole statement. The relevant miners remain the same set. Since restricts the circumstances in which the sentence is meaningful, but it doesn't restrict the relevant miners' deaths.
One final example. Consider it your final exam. Is an adverbial clause beginning with if restrictive or descriptive?
If the boss had spent more, the miners would still be alive.Restrictive; although a comma follows the if clause because it starts the sentence, the sentence is true only if the miners' lives depended on the spending.
Now all readers can follow the discussion about punctuation.