Calling on colons

Consider using a colon to join two, closely related independent clauses when you want to emphasize the second.

This year in the Legal Writing Tip column we have examined the use of two different punctuation marks—the comma and the semicolon—in forming compound sentences and the advantage of choosing the latter over the former when you mean to suggest a close relationship between two separate statements, as seen here: New York State Supreme Court Justice Arthur F. Engoron granted summary judgment to New York Attorney General Letitia James on the question whether Donald J. Trump committed fraud by overstating the value of his assets when seeking loans with favorable terms and other benefits; in deciding that no trial was needed to determine the claim at the heart of James’s civil action against the former president, the judge handed the attorney general a major victory.

In that example, the second independent clause adds detail to the first, and thus use of a semicolon in joining the two is appropriate. (An independent clause is a group of words containing a subject and verb that can stand alone as a complete sentence.)

There is a third punctuation mark that may be used to join two independent clauses in certain circumstances.  And that is the colon. As Richard Wydick explains in Plain English for Lawyers (5th ed.), a colon generally indicates that what follows is a summary, elaboration, or illustration of what precedes it.  This punctuation mark introduces information set up by the preceding clause, most often when what follows is a list, an example, or an explanation.  Accordingly, you can use a colon to join two, independent clauses when the second clause summarizes, explains, or gives an example of the first and you want to emphasize the second clause.

In The Elements of Legal Style, 2nd ed., legal writing expert Bryan Garner illustrates the impact a colon can have on the resulting compound sentence by advising us to consider the following two statements:

The commission prescribes two levels of qualification, one is for principals and the other is for registered representatives.

That is a grammatically incorrect sentence, in fact, a run-on, because the comma is not followed by a conjunction.  (While the sentence technically contains three independent clauses, no comma is needed after the word principals because the preceding and ensuing clauses are so short.)

Swap the comma for a semicolon, and you have a simple solution to the problem:

The commission prescribes two levels of qualification; one is for principals and the other is for registered representatives.

But, as Garner writes, “if you wish to emphasize how the second half of the sentence specifies the generalization of the first half—if you want to underscore for the reader how one half balances the other—then use a colon,” like so:

The commission prescribes two levels of qualification: one is for principals and the other is for registered representatives.   

Alternatively, he says, if you wish to emphasize the separateness of the two levels of qualification, trade the word and for a semicolon:

The commission prescribes two levels of qualification: one is for principals; the other is for registered representatives.  

Wydick gives us these two examples of compound sentences formed by a colon:

  • The DNA evidence is vital: it is our only proof that the defendant was at the scene.
  • The gasoline truck hit the wall: the gasoline explosion killed the driver.

In the first example, placement of the colon is appropriate, Wydick says, because the first statement introduces the second.  In the second example, a colon is suitable, he says, because the relationship between the two independent clauses is one of cause and effect.  Using a semicolon in lieu of a colon in these two examples would not be wrong, but it would not direct the reader’s attention to the second part of the resulting compound sentence with the same force.

According to the website Word Genius, colons and semicolons are distinct in that semicolons show evidence for a statement, while colons create emphasis or give an explanation.  Where the punctuation mark serves as a stand-in for a conjunction, use a semicolon to join the two independent clauses, as in this example:

Judge Engoran issued a gag order against Trump and his lawyers forbidding them from emailing or speaking publicly about his staff; earlier in the day in a social media posting, Trump had personally attacked the judge’s clerk, falsely referring to her as Senate Majority Leader Chuck Schumer’s girlfriend and included her photo.

In that sentence, the semicolon is the better choice; it stands in for the word because.

William Strunk and E.B. White provide two examples of compound sentences correctly formed by a colon in the third edition of The Elements of Style:

  • But even so, there was a directness and dispatch about animal burial: there was no stopover in the undertaker’s foul parlor, no wreath or spray.
  • The squalor of the streets reminded him of a line from Oscar Wilde: “We are all in the gutter but some of us are looking at the stars.”  

Use of a colon is appropriate in the first example, Strunk and White say, because the second clause “interprets or amplifies” the first.  The colon’s placement in the second is suitable because it introduces a quotation that “supports or contributes to the preceding clause.”  Exchanging the colon for a semicolon in the first example would also be acceptable, but the colon’s appearance indicates a closer relationship between the two clauses and makes the second stand out.  Opting for a semicolon in the second example, however, would be a grammatical gaffe because semicolons are never used to introduce quotes.

While Wydick, Garner, and Strunk and White put in lower case the first letter of the first word following a colon regardless whether the second clause could stand alone as a complete sentence (unless the first word of the second independent clause is a proper noun), other writing experts say that in the U.S.A., as opposed to the United Kingdom, capitalizing this letter is the customary practice.

When using a colon to introduce a list, rather than another group of words that could stand alone as a sentence, be sure that the words preceding the colon form an independent clause.  (It is not necessary to include the words as follows or the following before the colon.)  Never place a colon between a verb and its object or between a preposition and its object.

Correct: Prosecutors accused the man of committing three crimes: vandalizing public property, breaking and entering, and burglary.

Incorrect: Prosecutors charged: vandalizing public property, breaking and entering, and burglary.  (A colon should not appear here because it separates the verb charged from its three objects.)

Incorrect: Prosecutors charged the man with: vandalizing public property, breaking and entering, and burglary.  (The colon is misused in this sentence because it separates the preposition with from its three objects.)

Using colons or semicolons to form compound sentences has unfortunately become uncommon over the past decades as knowledge of the capabilities of these two punctuation marks has dwindled.  But now that you understand how to wield them, do not shrink from employing these punctuation marks judiciously to add variety or punch to your writing and make it more succinct.