In January, we discussed several frequently forgotten rules concerning correct placement of commas.  This month, we continue with that topic by looking at a few ways this punctuation mark should be used in sentence construction.

Place a comma after an introductory clause. 

In general, a phrase that appears before the main clause of the sentence should immediately be followed by comma.

Here are a few examples that Richard Wydick uses to illustrate this rule in his Plain English for Lawyers (5^th ed.):

• Wanting to settle the case quickly, the plaintiff authorized her lawyer to accept any amount over $5,000.
• At the time of the accident, the defendant was intoxicated.
• To the make the point clearly, she used a diagram.

And here is an example from Bryan Garner’s The Elements of Legal Style (2^nd ed.):  

• In waiving sovereign immunity, the legislature must express a clear intention to waive immunity against claims of a particular kind.

But if the introductory phrase is very short, you may omit the comma:

• At home he wears glasses instead of contact lens. (Wydick, Plain English.)

On this principle, Garner tells us, many expressions of time are not set off.

Here is his example:

• By October the debt had climbed to more than $10,000.

But if you add just one element to the date, a comma is required:

• By October 2001, the debt had climbed to more than $10,000.

Garner further illustrates his point by comparing these two sentences:

• In 1989 the Litigation Section was the ABA’s second largest.
• During most of the late 1980s, the Litigation Section was the ABA’s second largest.

Enclose parenthetic expressions between commas.

A parenthetic expression or parenthetical element is one that is “pertinent but not essential to the meaning of a sentence,” as Wydick explains in Plain English: “If a word, phrase, or clause could be deleted without affecting the meaning of a sentence, then set it off with commas.”

Here are his examples:

• The mayor’s indictment was, to say the least, unexpected.
• Freedom of speech is, after all, one of our most cherished rights.

And here’s an example from Strunk and White’s The Elements of Style (3^rd ed.):

• Partly by hard fighting, partly by diplomatic skill, they enlarged their dominions to the east and rose to royal rank with the possession of Sicily.

Strunk and White point out in The Elements that a name or title in a direct address is parenthetic:

• If, Sir, you refuse, I cannot predict what will happen.

Here’s Wydick’s example:

• We submit, Your Honor, that the injunction should be lifted.

Use commas to set off nonrestrictive clauses.

A nonrestrictive clause, as Strunk and White define it, is one that “does not serve to identify or define the antecedent [preceding] noun.”  Wydick explains that a nonrestrictive element within a sentence “modifies or describes part of the sentence but is not essential to the meaning.”  As such, it is a form of parenthetic expression, according to Strunk and White.

Here are three examples from Strunk and White:

• The audience, which had at first been indifferent, became more and more interested.
• In 1769, when Napoleon was born, Corsica had but recently been acquired by France.
• Nether Stowey, where Coleridge wrote “The Rime of the Ancient Mariner,” is a few miles away from Bridgewater.

In the three sentences above, the clauses introduced by which, when, and where are nonrestrictive; they add information without limiting or defining anything else in the sentence.

(They are also dependent clauses, meaning they contain a subject and verb but grammatically cannot stand alone.)

Wydick points out that elements beginning with which are usually nonrestrictive.

Here is his example:

• The car, which is blue, ran the red light.

A restrictive clause, in comparison, is essential to the basic meaning of the sentence and should not be enclosed between commas.  Elements beginning with that or because are usually restrictive:

• The car that ran the red light is blue.

Here’s an example from Strunk and White:

• People who live in glass houses shouldn’t throw stones.

In that sentence, the subject, people, is limited to those living in glass houses.  For that reason, the clause beginning with who is restrictive and should not be enclosed between commas.

That said, elements beginning with who are usually nonrestrictive, as Wydeck points out:

• His father, who is an engineer, arrived on Tuesday.

Determining whether a clause is nonrestrictive or restrictive can be tricky.  Try mentally eliminating it from the sentence, as Wydeck advises.  If the basic meaning then changes or becomes ambiguous, the clause is restrictive and should not be set off by commas, as seen in the following example from Plain English:

• The job that she was seeking was filled.

Use commas to set off transitional words and phrases.

Enclose transitional words like therefore, thus, furthermore, however, and moreover between commas when they appear in the middle of a sentence:

• The conclusion, therefore, is that attorney advertising deserves only limited protection under the First Amendment. (Wydick, Plain English.)

And place a comma after a transitional word when it comes at the beginning of the sentence:

• Therefore, attorney advertising deserves only limited protection under the First Amendment.

Place a comma before the second independent clause in a compound sentence.

An independent clause is a group of words containing a subject and verb that can stand alone as a complete sentence.

When linking two independent clauses joined by a conjunction such as and, but, or, nor, for, or yet, always put a comma immediately after the first clause and before the conjunction appears.

Here’s an example from Garner’s The Elements of Legal Style:

• The judge denied the motion to dismiss the charges, but she lowered the defendant’s bail.

And here’s an example from Wydick’s Plain English:

• The “worm” that the defendant inserted in the computer system multiplied a million-fold, yet the defendant claimed he did not intend to damage the system.

According to Wydick, this is the rule of punction that law students in his advanced legal writing course would violate most frequently.  All too often, writers forget to include a conjunction and thus create a “comma splice” or run-on sentence, which can be confusing to readers.

A final caveat: Do not use a comma if the subject is not expressed in the second clause, and the clauses aren’t particularly long.

Here are two of Garner’s examples from The Elements:

• The judge was perturbed by the defendant’s outbursts but maintained order.
• The good brief should address all the issues and should analyze them intelligently.

The comma is notably the most frequent troublemaker in legal writing.  Stay above the fray by wielding it correctly.

About the Author:

Attorney Savannah Blackwell is a former news reporter who covered government and politics for more than a decade, mostly in San Francisco. She can be reached at savannah.blackwell@gmail.com. Follow her on Twitter at @SavannahBinSF