Many of us had an English teacher that taught us that adding the final comma to a list was not necessary so we didn’t need to do it. And if you writing or reading for pleasure, and dollars and cents are not determined but how your sentence or clause within your sentence are interpreted, by all means drop the restrictive comma.
But if you are an a lawyer or other person charged with the responsibility that people will be making significant financial decisions based on the clarity of your writing, add the restrictive comma.
The “restrictive comma” is the one that ends a list. In the law, we often see lists insurance policies regarding the kinds of things that are and are not covered. In corporations, whether for profit or not for profit, such as homeowner associations, they are governing documents discussing what the corporation will and will not do, and what is and is not allowed. Often we see lists of this kind in employment agreements.
As a matter of practice, including the final comma in a list never takes away clarity. Failing to add it however, creates ambiguity or at least creates greater ambiguity than what might otherwise exist. For example, suppose there is a tax that says the following fruits are taxed at 1 cent per pound: Bananas, apples, limes and pineapples. Are pineapples and limes weighed together for the tax or are they weighed separately? If the list read, “Bananas, applies, limes, and pineapples” there is no ambiguity that limes and pineapples are weighed and taxed separately.
Another example. Suppose an homeowners association provides that the following is prohibited: Tents, outbuildings, gazebos and other structures of a temporary character cannot be used as residential dwellings on lots within the Association. Does this mean tents are allowed but not if used as a residential dwelling, or does it mean tents are prohibited? Were the list to read, “Tents, outbuildings, gazebos, and other structures of a temporary character cannot be used as residential dwellings….” it is clear that tents and outbuildings and gazebos, if a “structure of a temporary character,” cannot be used for residential purposes. There still exists the ambiguity whether the drafter intended to prohibit tents, outbuildings, gazebos, and other structures of a temporary character altogether and most especially if used for a residential purposes.
Because of these kinds of ambiguities, careful legal drafting requires use of the restrictive comma. Its also a good idea to have several people read something before its finalized to get a feel on how other may interpret what the drafter is drafting. Also, often it is a good idea to have an express statement of the drafter’s intent to guide the interpretation, since some documents are not interpreted until years after the the document was drafted. Fortunately, most state and federal legislative history is fairly accessible, often for free. But private documents, such corporate, business, employment, and insurance documents often lack a readily accessible source of the drafter’s intent.
The point? If you are in the position of making a list, add the final comma before the final “and” or “or.” And, if you have to take a position in litigation, be aware that the omission of the restrictive comma may support or defeat your argument. Generally, courts will follow the rules of grammar in construing a sentence unless the judge’s “common sense” tells him or her that the drafter intended but omitted the restrictive comma.