You know: the comma before “and” in a list of three or more items.
The two main rationales for choosing one style over the other are clarity and economy. Each side has invoked both rationales in its favor. Here are some quotes that have served as shots exchanged in the Oxford comma wars.
Pro: “She took a photograph of her parents, the president, and the vice president.”
This example from the Chicago Manual of Style shows how the comma is necessary for clarity. Without it, she is taking a picture of two people, her mother and father, who are the president and vice president. With it, she is taking a picture of four people.
Quite. The “Oxford” comma is necessary there; it simply does one of the jobs a comma is supposed to do.
Con: “Those at the ceremony were the commodore, the fleet captain, the donor of the cup, Mr. Smith, and Mr. Jones.”
This example from the 1934 style book of the New York Herald Tribune shows how a comma before “and” can result in a lack of clarity. With the comma, it reads as if Mr. Smith was the donor of the cup, which he was not.
Ok well I tell you what, that’s not a good sentence, with or without the comma. Just re-do the sentence. That’s the other way to fix these little problems – just re-do the damn sentence.
The commodore and the fleet captain were at the ceremony, along with the donor of the cup (Susan Milligram) and Steve Jones and Bob Smith.
Still not elegant, but at least you can figure it out without getting a crick in your neck.