In Defense of “Nutty” Commas | Mary Norris, The New Yorker

The column focuses on two uses of the comma, including the serial comma (also called the Oxford comma)--the comma that goes before the conjunction in a listed series of things:

Nobody is really arguing about the serial comma. We like it because it prevents ambiguity. For instance, “I invited my boss, her nephew and my acupuncturist to the party.” Without the serial comma, one might mistake my boss’s nephew for my acupuncturist. This would be misleading, if only momentarily: Sam is a nice kid, but I would never let him near me with a needle. With the serial comma, there is no ambiguity: “I invited my boss, her nephew, and my acupuncturist to the party.”

I immediately noticed another potentially misleading ambiguity caused by inserting the comma after "nephew": Some readers might think "her nephew" is a descriptive phrase about "my boss."

If the writer really wanted to prevent confusion, she could have written: "I invited three people to the party: my boss, her nephew and my acupuncturist." In that case, the serial comma would not be needed.

As a former journalism student, newspaper editor/reporter and journalism instructor, I learned long ago that Associated Press style is to drop the serial comma in simple lists. Critics of that style don't know or forget that AP says to include the comma in complicated sentences.

Other than writing news releases occasionally, I haven't worked in the news biz for years. But I continue to follow AP's optional choice for using the serial comma. If using the comma could aid readers in complicated sentences, I don't hesitate to use it.

That said, always using the comma is never wrong (unless it goes against your publication's adopted style). But it's worth checking its use to see if the ambiguity I pointed out above might result by inserting the comma.