Sentence problems 9--faulty parallelism

"Express related ideas in parallel form" is common writing advice. Easier said than done, it seems. So let's be explicit: when you express a series of items, phrases, or ideas, parallelism requires two things:

1. Each item, phrase, or idea must flow naturally from the lead-in, and
2. All items, phrases, and ideas in the series must begin with the same part of speech.

One way to check your parallelism is to tabulate the phrases and check that each flows from the lead-in and that the first word in each is the same part of speech: verb, preposition, or noun. Here's an example:

• A lawyer must disclose adverse authority that is known to him, arises from the controlling jurisdiction, and that was not disclosed by opposing counsel.

As tabulated--

• A lawyer must disclose adverse authority that
  is known to him,
  arises from the controlling jurisdiction, and
  that was not disclosed by opposing counsel.

This sentence has flaws in both requirements of parallelism:

1. The third tabulated item does not follow from the lead-in:
   that . . . is known,
   that . . . arises from,
   that . . . that was not disclosed (this one doesn't work)
   
   
2. The beginning words are not in the same grammatical form:
   is and arises are verbs;
   that is not a verb.

Consider two ways to fix these problems. Repeat the lead-in word each time:

• A lawyer must disclose adverse authority that is known to him, that arises from the controlling jurisdiction, and that was not disclosed by opposing counsel.

Or revise so that the first words of the items are in the same grammatical form:

• A lawyer must disclose adverse authority that is known to him, arises from the controlling jurisdiction, and was not disclosed by opposing counsel.

Here's another:

Poor: Now that you are in law practice, you are a professional writer, and you should be aware of writing sources, usage dictionaries, and strive to improve your writing style.

Better: Now that you are in law practice, you are a professional writer, and you should be aware of writing sources, consult usage dictionaries, and strive to improve your writing style.

--Excerpted from Better Legal Writing