I’m here to tell you two things:
- Unless you are following a style guide that requires it—Chicago Manual of Style, American Psychological Association (APA), or American Medical Association (AMA)—the Oxford comma is optional.
- You should just use it anyway.
What is the Oxford Comma?
Sometimes called a serial comma, the Oxford comma is the last comma within a series or list in a sentence. For example:
- This store sells groceries, clothing, and electronics.
The comma after “clothing” is the Oxford comma. Here is the sentence without it:
- This store sells groceries, clothing and electronics.
According to the Associated Press (AP), Canadian Press (CP), and—surprisingly enough—the University of Oxford style guides, the sentence is correct without the Oxford comma.
In this case, the meaning of the sentence is clear either way. However, there are situations in which the absence of an Oxford comma can cause unintended ambiguity in your writing. For example:
- I went shopping with my parents, Beyoncé and Victor Frankenstein.
Are Beyoncé and Victor Frankenstein the parents? Maybe. How about this sentence:
- I went shopping with my parents, Beyoncé, and Victor Frankenstein.
With the Oxford comma, it is clear that the writer went shopping with Beyoncé and Victor Frankenstein as well as with his/her parents. Here’s another example:
- This design comes in red and black, gray and purple and black and white.
What? Let’s try that with an Oxford comma:
- This design comes in red and black, gray and purple, and black and white.
Now it is clear the design comes in three color schemes, each with two colors.
A $5 Million Mistake
One last piece of evidence regarding the clarity an Oxford comma can provide comes from a lawsuit settled by a dairy company in Maine. Three truck drivers sued the company, claiming they were owed four years’ worth of overtime. According to Maine state law, workers were not eligible for overtime pay for:
“The canning, processing, preserving, freezing, drying, marketing, storing, packing for shipment or distribution of: (1) Agricultural produce; (2) Meat and fish products; and (3) Perishable foods.”
Without a comma after “shipment,” the law seems to apply to packing for shipment or distribution, not to the actual distribution. The judge concurred, and the company settled the case, agreeing to pay $5 million to the drivers.
Omitting the Oxford comma can be a costly mistake. When in doubt, just use it.