The Enigmatic Em Dash

Knowing how to punctuate properly is essential to good legal writing. Besides the semicolon, though, lawyers probably misunderstand—and as a result misuse—the em dash more than any other punctuation mark. That’s because it’s possible for a lawyer to write for an entire career without ever having to use it.

But lawyers who consciously avoid using the em dash forsake an important legal-writing tool. They’re like carpenters who choose to work with rudimentary tools instead of precision instruments. The job gets done; but the result is hardly refined.

What’s an em dash?

The em dash (—) is about as wide as a capital H. In Typography for Lawyers, Matthew Butterick dispels the myth that the em refers to the letter M. According to Butterick, the em instead refers to units of typographical measurement: “In a traditional metal font, the em was the vertical distance from the top of a piece of type to the bottom.”

The origin of the em dash is unclear. Noreen Malone, in The Case—Please Hear Me Out—Against the Em Dash recounts speculation that the em dash has existed since the Gutenberg printing press (ca. 1450s) but she also notes that it didn’t routinely appear in print until the 1700s. If true, the em dash is a recent invention compared to other punctuation marks such as the period and comma.

Em dash as utility infielder

The em dash is a versatile punctuation mark, somewhat like baseball’s utility infielder. Besides doing their own work in a sentence, em dashes can substitute for commas, parentheses, and even colons to mark a variety of interruptions.

In Writing with Style, John Trimble lists five different circumstances where em dashes can mark interruptions. I’ve listed them below, along with usage examples:

  1. Marking an interruption or break in thought: Writers overuse em dashes—well, to be fair, careless writers overuse them.
  2. Serving as a conversational colon or light bridge: One writer is known for using em dashes haphazardly—Emily Dickinson.
  3. Isolating a concluding phrase for emphasis or comic effect: Punctuating properly is necessary to write well—unless, of course, that’s not your goal.
  4. Marking a gathering-up of ideas or series of subjects: Avoiding buried verbs, minimizing prepositions, using the active voice—these are easy ways to improve writing.
  5. Inserting a parenthetical explanation, qualification, or amplification: The leading authorities on American legal writing—Wydick, Garner, and Kimble—agree that em dashes are an excellent way to set off parenthetical or explanatory material.

Skilled legal writers usually limit their em dashes to Trimble’s fifth circumstance because the other four, which all require a single dash and force the reader to stop abruptly, occur less often in legal writing.

But consider number five above. Notice how commas or parentheses wouldn’t have the same attention-grabbing effect on the explanatory phrase:

  • The leading authorities on American legal writing, Wydick, Garner, and Kimble, agree that em dashes are an excellent way to set off parenthetical or explanatory material.
  • The leading authorities on American legal writing (Wydick, Garner, and Kimble) agree that em dashes are an excellent way to set off parenthetical or explanatory material.

Sentences such as this one call for a pair of em dashes. Commas or parentheses—while grammatically acceptable—simply don’t do the job.

Misusing em dashes

Like other writing tools, lawyers can misuse the em dash. Here are some things to avoid.

  • Don’t use more than two em dashes in a sentence. Otherwise, as Trimble points out, “[y]ou’ll simply confuse your reader, and your prose will look like chopped carrots.”
  • Don’t litter your writing with em dashes. In The Practical Stylist, Sheridan Baker puts it best when he says that overusing em dashes is a “sign of ignorance, or of laziness.” In Woe is I, Patricia T. O’Conner says that too many em dashes signify unclear thinking: “[W]hen thoughts are confused, it’s easier to stick in a lot of dashes than to organize a smoother sentence.” So don’t give the critics of the em dash more fodder; after using an em dash, take a break for three or more sentences before using another one.
  • Don’t call one or two hyphens an em dash. Novices take the hyphen shortcut, perhaps assuming that their readers won’t notice the difference. Typing two hyphens was a common way to indicate an em dash when lawyers used typewriters. But modern word-processing programs can directly insert an em dash into a document. In Microsoft Word 2010, you can insert an em dash by selecting the Insert tab and then the Symbol subtab. If you have a Mac with Word, you can insert an em dash by simultaneously pressing the Option + Shift + Hyphen keys.

Em dashes add energy, variety, polish

Now that you know the basics, consider trying out the versatile em dash. You’ll find that the em dash adds energy—and much needed variety—to your prose. The em dash also gives you another option when the standard commas, parentheses, or colons don’t quite strike the desired tone. Like a carpenter with precision tools, em dashes will polish your prose and make your legal writing stand out from the mediocre.

This column is adapted from an article originally published in the Minnesota Lawyer on July 1, 2013.


  • 2013-07-13. Originally published.
  • 2014-10-22. Republished.
Matthew Salzwedel
Matthew R. Salzwedel is a former lead managing editor of the Minnesota Law Review. After law school, he clerked for the Minnesota Court of Appeals and practiced commercial and antitrust litigation in Minneapolis and Philadelphia. He now is corporate counsel at a Minneapolis-based company.