The Oxford (or serial) comma is a comma used before the final conjunction in a list of three or more items. When you’re writing a list, commas are added to separate each item, but the Oxford comma is when you also put a comma before the ‘and (final item)’. Here is an example to show you how it helps with distinguishing unrelated items in a list –
‘Her favourite foods are salmon, broccoli, apples and chicken’ (without Oxford comma)
‘Her favourite foods are salmon, broccoli, apples, and chicken’ (with Oxford comma)
The use of the Oxford comma is helpful to separate two very different foods which bear no relation to each other. Indeed, the Oxford comma can be a vital tool to avoid dangerous ambiguity. To show you how this can cause problems, there was a case in the US in which Maine state law sought to exempt employers from paying overtime for ’canning, processing, preserving, freezing, drying, marketing, storing, packing for shipment or distribution’. The packing that was required for distribution as well as for shipment would have cost employers a fortune.
Here’s another example –
‘I love my parents, my dog and my cat’
Without the Oxford comma, you might think that you are saying you love your parents and that your parents are your dog and your cat. With the Oxford comma, this potential confusion is removed –
‘I love my parents, my dog, and my cat’
Obviously, discretion should be used, as there are plenty of occasions when there’s no ambiguity – ‘On our holiday, we travelled to France, Germany, Spain and Italy’. So I’d advocate using it on a case-by-case basis – that way, your meaning will always be clear.
