The Oxford comma is a comma before the final item in a list. For example, it’s the one after “toast” in this sentence:  “We had eggs, toast, and oatmeal for breakfast.” If you left out the Oxford comma, it would read “We had eggs, toast and oatmeal for breakfast.”

It’s also called the “serial comma,” and there’s a big article about it on Wikipedia. Why? Because there’s an ongoing squabble among writers and grammarians about whether one should use it.  A summary of the issues at hand is in the Wikipedia article, to wit:

Common arguments for consistent use of the serial comma:

1. Use of the comma is consistent with conventional practice.
2. It matches the spoken cadence of sentences better.
3. It can resolve ambiguity (see examples below).
4. Its use is consistent with other means of separating items in a list (for example, when semicolons are used to separate items, a semicolon is consistently included before the last item even when and or or is present).
5. Its omission can suggest a stronger connection between the last two items in a series than actually exists.
6. Its use can “prevent any misreading that the last item is part of the preceding one”.

Common arguments against consistent use of the serial comma:

1. Use of the comma is inconsistent with conventional practice.
2. The comma may introduce ambiguity (see examples below).
3.  Where space is at a premium, the comma adds unnecessary bulk to the text.

You can see examples of all of these issues in the article, but I find the arguments for its use to be stronger. In my view, the comma resolves ambiguity more often than it creates it. And as for “inconsistent with conventional practice”, that doesn’t cut any mustard with me, nor does “adding unnecessary bulk to the text.” Unnecessary bulk is less important than clarity.

Now, however, the Oxford comma has been ruled as “necessary”—in at least one case—by a COURT. To see the case and the decision, read the article below from The Write Life:

The issue, decided by an appellate court in Maine, was about whether drivers for a dairy in Maine were entitled to get paid overtime for some types of work. According to state law, drivers are supposed to get 1.5 times their normal pay for working overtime (more than 40 hours per week). But the law spells out some exceptions. You do not get special overtime pay for the following:

The canning, processing, preserving, freezing, drying, marketing, storing, packing for shipment or distribution of:

1. Agricultural produce;
2. Meat and fish product; and
3. Perishable foods

Note the absence of a comma after “shipment” in the phrase “packing for shipment or distribution”. This creates ambiguity. If there was an Oxford comma after “shipment”, then the drivers would not be entitled to pay for either “packing for shipment” OR for “distribution”, two separate activities. If the Oxford comma was not placed after “shipment”, as it stands, then drivers wouldn’t get paid for “packing for shipment or distribution”, one packing-related activity, but could get paid for distribution itself, which doesn’t involve packing.

So here the absence of a comma created an ambiguity. Are drivers supposed to be paid overtime for distributing a product or not? The Oakhurst Dairy said no: that the exemption from overtime pay, despite the absence of a comma, was intended to cover the activities of both “packing for shipment” and “distribution”. The drivers disagreed, saying that the absence of a comma meant that “packing for shipment or distribution” meant a single packing-related activity, and that they should be paid overtime for “delivery.”

The drivers won. As the site reports:

Without that comma, as the judge maintained, this distinction was not clearcut:

Specifically, if that exemption used a serial comma to mark off the last of the activities that it lists, then the exemption would clearly encompass an activity that the drivers perform. And, in that event, the drivers would plainly fall within the exemption and thus outside the overtime law’s protection. But, as it happens, there is no serial comma to be found in the exemption’s list of activities, thus leading to this dispute over whether the drivers fall within the exemption from the overtime law or not.

As a result, the court found in favor of the drivers, costing the dairy an estimated $10 million.

I think that settles it, as it’s a legal judgment about how to resolve issues when the absence of a comma creates ambiguity.

I always use the Oxford comma unless my mind slips, and so I agree with this usage. Note, however, that in some instances the comma can create ambiguity or fail to resolve ambiguity. In most cases I run across, however, the comma is useful in resolving ambiguity, and so I use it. If I see ambiguity remaining with such use, I resolve it another way.

So the absence of an Oxford comma has cost a dairy $10 million. It’s not the dairy’s fault, but the fault of those benighted legislators who wrote the law. Bad punctuation can have serious consequences!

And I’m not even mentioning the “grocer’s apostrophe”, which really gets my knickers in a twist:

So I was reading a book this evening that mentioned a Canadian hockey team, the Toronto Maple Leafs. Yes, I know that team, and always thought the name sounded curious, but then I thought, “Why isn’t it Maple Leaves?” After all, the plural of “leaf” is “leaves”.

Now you might say that the word “Leafs” is not a plural, but simply the name of the team. But that doesn’t make sense either, as there is no noun “leafs.” And suppose the team was named after an appropriate waterfowl, the Canada Goose. Would they call the team “The Canada Gooses”? No, they’d call it the “Canada Geese“.

Now I’m sure there’s an explanation for this, and that a Canadian reader will school me. But I’m still puzzled.