Consider the following sentence:
We fed the puppies, Bobbles, and Fluffy.
In English, for lists of more than three items, the items are separated by commas, that is, all except for the last item, which must be separated by the word “and.” The “and” signals that this is the end of the list. However, is it also necessary to use a comma in this case?
We fed the puppies, Bobbles and Fluffy.
In British English and much English taught in Asian countries, it is not necessary. The “and” takes the job of the separator, so a comma is seen as redundant.
I used to write this way as well. However, not using the Oxford comma can lead to situations in which the text is ambiguous. This is because a comma has more than one purpose in English. In addition to separating a list, a comma can separate two parts of a sentence.
So the above sentence could be interpreted to mean that we fed two puppies, one named Bobbles, and one named Fluffy, when we really meant that we fed the puppies, and then we fed two more pets, one pet named Bobbles and one pet named Fluffy, who are different from the puppies.
A recent court case that hinged on the Oxford comma was recently decided in the favor of delivery drivers who wanted overtime pay. The regulations were written in a similar way to the above. The regulation that stated what is not covered by overtime is as follows:
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
They meant that both packing for shipment and distribution are not covered by overtime pay. However, this sentence could be read as packing for shipment and packing for distribution are not covered by overtime pay. Hence, distribution must be covered.
The court ruled that the comma was needed, and therefore overtime should be paid to the drivers who distributed the goods.
It is hence best to use the Oxford comma, especially in academic writing, where the precise interpretation of text is essential. It is also recommended even when writing in British English.