The Serial Comma Is Not a Rule, and Both Sides Know It

The serial comma — the one before and in red, white, and blue — is the most argued-about mark in English punctuation, and the argument is almost entirely fake.

It is fake because both positions are correct. It is heated because the people holding them have usually been told, by someone they trusted, that only one of them is.

What each side actually says

The Chicago Manual of Style uses it. So do most book publishers, most academic presses, and Oxford University Press — which is where the alternative name, the Oxford comma, comes from.

The Associated Press Stylebook does not, except where a sentence would otherwise be unclear. So most newspapers, most magazines, and a great deal of web writing follow suit.

Neither is a grammar rule. Both are house conventions, and the houses simply chose differently. If you have been taught that one is correct, you were taught a style guide, not the language.

The famous ambiguity argument

The case for the serial comma is usually made with a joke:

We invited the strippers, JFK and Stalin.

Without the comma, the sentence can be read as naming the strippers. With it — the strippers, JFK, and Stalin — the list is unambiguous. Point made.

Except the joke cuts both ways, and the other version is less well known:

We invited the stripper, JFK, and Stalin.

Now the comma has created the ambiguity: is JFK the stripper, in apposition? Add a serial comma to a list whose second item could be a description of the first and you get exactly the confusion you were trying to avoid.

So the honest version of the argument is not the serial comma prevents ambiguity. It is the serial comma prevents one kind of ambiguity and creates another. Which kind you meet more often depends on what you write.

The case that is not made often enough

Ambiguity is the argument people reach for, but it is not the real reason either side holds its position.

The real argument for it is consistency. If you always use it, you never have to stop and judge whether a particular list needs it. One fewer decision per sentence, and no risk of the reader wondering whether an omission was meaningful.

The real argument against it is space and speed. AP style was built for newspaper columns, where characters cost money and a comma that adds nothing is a comma worth cutting. That reasoning is weaker on the web, which is why the newspaper convention has spread less than you might expect into online writing.

A real court case, since one always comes up

In 2017 a group of dairy drivers in Maine won an overtime dispute that turned on a missing serial comma in a state law listing activities exempt from overtime pay. The list ended with packing for shipment or distribution. Without a comma, it was unclear whether distribution was a separate exempt activity or merely a kind of packing. The drivers distributed; they did not pack. The court found the clause ambiguous and ruled for them.

It is a genuinely good story and it proves less than it is usually made to prove. It shows that in legal drafting, ambiguity is expensive — which is why legal style guides overwhelmingly require the serial comma. It does not show that ordinary prose needs it. Maine later amended the statute, incidentally, not by adding a comma but by rewriting the list with semicolons.

What to actually do

Writing for a publication? Use its style guide. This is not your decision to make and nobody will thank you for making it.
Writing anything legal, contractual, or technical? Use it. The consistency is worth more than the character.
Writing for yourself? Pick one and hold it. The inconsistency is the only thing a reader will actually notice.
Writing a list that is going wrong either way? Stop punctuating and start rewriting. Reorder the items, or break the sentence in two. Almost every famous serial-comma ambiguity dissolves the moment someone reorders the list.

The part worth remembering

Nobody is wrong here. If someone tells you the serial comma is required, they mean it is required in their house style. If someone tells you it is redundant, they mean their house style omits it. Both are describing a preference and calling it a rule, which is the most common thing that happens to punctuation advice in English.

Learning to hear that difference — rule, convention, or someone’s preference — is worth more than the answer to this particular question.