The authorities disagree, so a checklist has to name one
The United States Government Publishing Office requires a comma after each member within a series of three or more words, phrases, letters, or figures used with and, or, or nor. Its own example is "red, white, and blue".2 That is the serial comma, and for federal publications it is not optional.
Maine's legislature does not follow the same practice. The First Circuit's opinion observes that guidance on legislative drafting in most other states, and in Congress, appears to differ from Maine's on serial commas. Some state drafting manuals expressly warn that omitting the serial comma can create ambiguity about the last item in a list. The opinion also cites a published analysis counting only seven states, Maine among them, that either do not require the serial comma or expressly prohibit it.1
Two American authorities, both careful and both published, instruct writers to do opposite things. A checklist that says "use the serial comma" is not stating a rule of English. It is naming a house style, and it is only correct for documents written to that house.
What a checklist can settle
Three categories survive that objection, and everything worth checking falls into one of them. The first is the small set of items where the authorities agree, so that a violation is an error under any of them. Examples include a sentence with no finite verb, a subject and verb that disagree in number, a possessive apostrophe on a plural that is not possessive, and a quotation opened and never closed.
The second is conformity to the authority the document has chosen. Once a manuscript has named its style manual, that manual settles the serial comma, the treatment of numbers, the capitalization of headings, the format of dates, and the reference style. Each of those then becomes checkable against a written source rather than against an opinion.
The third, and the largest in practice, is internal consistency. Copy editing is defined by Editors Canada as including checking for and correcting errors and inconsistencies, checking mechanical consistency, and developing the style sheet on which those decisions are recorded.3 The Editorial Freelancers Association describes copyediting in the same terms, down to the style sheets that guide consistency across a manuscript.4
Consistency is checkable without any authority at all, because the document supplies its own standard. A manuscript that hyphenates a compound in chapter one and leaves it open in chapter nine has a fault no style manual is needed to identify.
The items worth running through, in the order they pay
Reference lists and in-text citations are checked against each other in both directions, so that every citation has an entry and every entry is cited. It needs nothing but the manuscript and an hour. Abbreviations come next, each defined once, at first use, and not redefined later. The International Committee of Medical Journal Editors asks for standard abbreviations only, notes that nonstandard ones confuse readers, and advises against abbreviations in titles.5
Numbers, dates, and units follow one convention throughout the document, and ICMJE asks for metric units for length, height, weight, and volume, with temperatures in degrees Celsius.5 Names are spelled and capitalized the same way on every appearance, including in captions and in the notes, where a house style is easiest to forget.
Cross-references, headings, and numbering are checked after the final reordering rather than before it, because reordering is the operation that breaks them. Quotation marks, parentheses, and brackets are counted, since each of them has to close. None of those checks requires an opinion about the writing, which is why they can be delegated and why they are worth doing last.
The limit of any list, including this one
A checklist tests what can be stated as a rule. It cannot tell whether a sentence means what its writer intended, and the Maine statute is the demonstration. Every item in that list was correctly spelled and correctly capitalized. The sentence was ambiguous anyway, and it took three federal judges to say so.
Everything a client sends is treated in confidence, including drafts, contracts, and correspondence. EditFast works to whichever style authority a client has chosen, records the decisions on a style sheet, and returns that sheet with the manuscript. Interpreting a contract, a statute, or a regulation is a matter for the client's own advisors rather than for an editor.
What a reader adds to a checklist is the observation that a sentence can be read two ways. No list yet written can be given that job.