In favor of the serial comma
I favor using a full complement of serial commas:
The flag is red, white, and blue.I put a comma before the conjunction in a series of three or more items. I haven't found any legal-writing source that says you can omit that comma. And I haven't yet been persuaded that including that comma ever causes a problem, though some have tried to persuade me.
Here's an example in which omitting it causes a miscue:
For property owners to be liable, they must know of a danger, the danger must not be apparent to the public and the owner must chose not to warn others of the danger.Did you catch the miscue?