Comma placement can cause a big effect in legal documents. (See “What Broadway’s Hamilton Teaches About Legal Interpretation.”) In particular, whether or not to place a comma before the word “and” frequently leads to errors.
Use the Serial Comma
When you list three or more items, the best practice is to include a comma before the last “and.” For example:
Notice was served on the tenants, John Doe and Jane Roe.
In this case, how many people were served? Are John and Jane the tenants? Or was service made on them in addition to being made on the tenants?
The issue in this sentence is the absence of the serial comma (also called the Oxford comma). The sentence in the example above is technically correct (the last comma before the “and” is optional), but it is confusing without extrinsic evidence — a situation lawyers should always shun. As it is currently written, it could be assumed that John Doe and Jane Roe are indeed the tenants. But note how including the comma minimizes confusion:
Notice was served on the tenants, John Doe, and Jane Roe.
Don’t be afraid to re-order a list or revise a sentence for the greatest clarity:
Notice was served on John Doe, Jane Roe, and the tenants.
Take Out the Compound Predicate Comma
A compound sentence takes a comma; a compound predicate does not. Legal writing often includes compound sentences comprising two independent clauses linked by the word “and”:
Larry Landlord served notice, and he contacted his lawyer to start eviction proceedings.
Both parts of this sentence include a subject and verb; either part could stand on its own. Divide the two parts of a compound sentence with a comma before the “and.”
On the other hand, do not separate a subject from its verb:
Larry Landlord served notice and contacted his lawyer to start eviction proceedings.
When a subject has two verbs, grammarians say this sentence has a compound predicate. The same subject is doing multiple things.
Exceptions, Always Exceptions
In long sentences, other rules governing commas can get in the way:
Larry Landlord served notice, a state requirement, and contacted his lawyer to start eviction proceedings.
Here “a state requirement” is an appositive, a noun phrase to explain the adjacent noun. The commas are there to set off the appositive; that they also come between the subject and its verb is incidental.
Here’s another exception: The don’t-separate-a-subject-from-its-verb rule doesn’t apply if the link is “but”:
Larry Landlord served notice, but did not contact his lawyer to start eviction proceedings.
Long sentences can get tricky, which is why it’s best to break them up. Regardless of the length of your sentences, start from the two basic rules: Include the serial comma, and don’t separate a subject from its verb.