Use Dashes Around a List When the Sentence Continues After It
The Colon
Rulebase Summary
When a list is separated by commas and the sentence continues after the list, use a pair of dashes to surround the list rather than a colon in front of it. A colon would leave the reader stranded mid-sentence with no clear way to resume. Dashes cleanly set off the list and allow the sentence to continue.
Examples
A. The items: the laptop, the phone, and the tablet were all entered into evidence.
A. The items -- the laptop, the phone, and the tablet -- were all entered into evidence.
Dashes surround the list; sentence continues.
A. Several witnesses: Dr. Lee, Ms. Holt, and Mr. Franco testified on Tuesday.
A. Several witnesses -- Dr. Lee, Ms. Holt, and Mr. Franco -- testified on Tuesday.
Dashes let the sentence resume after the list.
Transcript Notes
This comes up when a witness names several items in the middle of a longer thought. If the sentence keeps going after the list, a colon before the list will mislead the reader into thinking the sentence ended. Use dashes around the list instead.
The colon becomes incorrect when the sentence continues after the list because the rule requires the entire sentence to precede the colon. If you removed the list, you would be left with a colon stranded in the middle of a sentence — an obvious misuse. Dashes solve this cleanly by enclosing the list while letting the sentence resume on the other side.
Style Guide References (1)
BGGP