Sometimes the smallest thing – like a misplaced comma – can cost a company a lot. In one case it is an estimated $10 million.

This happened after Oakhurst Dairy in Portland, ME, was sued in 2014 by three of its truck drivers, who accused their employer of failing to pay overtime as required by state law.

The case boiled down to the lack of a serial comma, also called an Oxford comma, as it appears in “planes, trains, and automobiles” instead of “planes, trains and automobiles.”

(In this publication we have dropped the serial comma with one exception: when the items come in dual sets, such as “helicopters, planes, passenger and freight trains, and automobiles and trucks.”)

The Maine overtime law does not apply to “The canning, processing, preserving, freezing, drying, marketing, storing, packing for shipment or distribution of: (1) Agricultural produce; (2) Meat and fish products; and (3) Perishable foods.”

Does the law exempt the distribution of the three categories that follow, or does it mean to exempt packing (which the drivers don’t do) separately?

“Whether the drivers were subject to a law that had denied them thousands of dollars a year depended entirely on how the sentence was read,” notes Daniel Victor, writing in the New York Times (which doesn’t use the serial comma, either).

If the law had included a comma following “shipment” it might have been clear that it exempted the distribution of perishable foods.

A federal appeals court on March 13 sided with the drivers, saying the absence of a comma produced enough uncertainty to rule in their favor.

Perhaps providing basis for an appeal is the fact that the law follows guidelines set by the Maine legislature, which tell lawmakers not to use the Oxford comma. Don’t write “trailers, semitrailers, and pole trailers,” it instructs – instead, write “trailers, semitrailers and pole trailers.”