If you attended a U.S. elementary school in
the 1970s and ’80s, you may have evaded formal instruction in English
grammar and punctuation. I know that I did. Fortunately, many of us
absorbed the most important rules—the ones that ensure clarity—from
reading and, if we were lucky, from good written feedback on our later
written work. But if you had asked me in 1995 to define “comma splice,”
you would have received a blank stare. 1
You also may have learned that you should use a comma whenever you
might pause in reading a sentence aloud. That rule made sense to me until
I started listening more closely to how people talk. Either there must
be some additional rule, or Vince Vaughn and Christopher Walken must
punctuate the same sentence very differently. 2
What rules apply, then, for comma usage? I find it easiest to remember
the six primary situations in which it is appropriate to use a comma. If I
recognize one of those situations, I insert a comma. If I do not recognize
one of those situations, I omit (or delete) a comma that might otherwise
tempt me. Those six primary occasions are:
• To separate words or phrases in a series of three or more
• To separate two independent clauses joined by a coordinating
• To set off a nonessential element
• To set off introductory matter
• To separate coordinate adjectives and adverbs
• To set off a direct quotation of 50 words or fewer
I discuss the first three occasions in this month’s column; we’ll tackle
the other three, and a few other less complicated examples, next month.
1. Use a comma to separate words or phrases in a series of three or more.
You may remember this rule from the Great Oxford-Comma Debate of
the Summer of 2014.3 Even if you scorn my sage counsel and omit that
crucial Clarity Comma4 before the final and, you still must use a comma
to separate the other words in the series. For example:
• The defense called four witnesses: the defendant, the
defendant’s mother, the defendant’s sister, and the
• Petey has shredded several shoes, the wall, and my
• The witness testified that she saw Mr. Acme pick up the
anvil, toss it over the cliff, and flee the scene.
2. Use a comma to separate two independent clauses joined by
a coordinating conjunction. By doing so, you create a com-
pound sentence. An independent clause is one that includes a
subject and a verb and expresses a complete thought; it could
stand alone as a complete sentence. Coordinating conjunctions
include for, and, nor, but, or, yet, and so. For example:
• Kevin’s client wanted to go to trial, so he rejected the
State’s plea offer.
• No disputed issue of material fact exists, and the Court
can decide this issue as a matter of law.
People most often err in applying this rule by failing to notice
that they do not have an independent clause on each side of the
coordinating conjunction. For example, you would not use a
10 ARIZONA ATTORNEY OCTOBER 2015 www.azbar.org/AZAttorney
THE LEGAL WORD by Susie Salmon
Susie Salmon is Assistant Director
of Legal Writing and Associate Clinical
Professor of Law at The University of
Arizona, James E. Rogers College of Law.
Before joining Arizona Law, she spent
nine years as a commercial litigator at
large firms in Tucson and Los Angeles.
comma in these instances:
• Kevin’s client wanted to reject the
State’s plea offer and go to trial.
• Jennifer scorned grammar and often
made punctuation errors.
People also err here by omitting the coordinating conjunction, which creates a comma
splice because a lone comma lacks the
strength to adhere two independent clauses. 5
3. Use a comma to set off a nonrestrictive
clause or other nonessential elements—such
as interrupting words or phrases like however
or of course—from the rest of the sentence,
whether those elements come at the begin-
ning, middle, or end of the sentence. A non-
restrictive clause is one that could be omitted
from the sentence without changing the
essential meaning of that sentence. Some
people refer to the nonrestrictive clause as
parenthetical matter; it generally clarifies or
explains something in the sentence, but the
sentence stands without it. For example:
• Moose, who was a much better puppy
than Petey is, only chewed furniture
• If you always use the clarity comma,
however, its omission conveys
• Sobbing, the witness fled the stand
after Walt’s devastating cross-examination.
Mindful comma usage enables you to control the meaning and flow of your writing.
Stay tuned for more examples of how to kick
that drum correctly and effectively.
1. Now, you receive a column on the topic.
2. They might.
3. If you’re not doing so already, you should
be reading the diverting and informative AZ
Attorney blog. Tim Eigo covers one of our
few disagreements—over that oh-so-essential
comma before the and in a series—in
the July 31, 2014, installment at
He also links to my April 2014 column on
4. Should I trademark my rebranding effort?
(Editor’s note: Yes.)
5. See my June 2014 column for more on the
No Comma Drama (Part One)