PORTLAND, Maine — A Maine labor dispute appeal decided on Monday hinged on perhaps the nerdiest, most contentious punctuation debate of all — the Oxford comma.

The U.S. First Circuit Court of Appeals ruled in favor of a group of Oakhurst Dairy truck drivers, who sued the company’s owners three years ago for unpaid overtime wages. The decision overturns an earlier U.S. District Court judgment in Oakhurst’s favor, keeping alive the dispute over $10 million in overtime wages for 75 Oakhurst drivers.

“For want of a comma, we have this case,” reads the opening line of First Circuit Judge David Barron’s 30-page decision.

The Oxford comma, also known as the serial comma, is used just before a conjunction, such as “and” or “or,” to separate the last item in a list of three or more things.

For example: “He bought milk, toast, and eggs.”

It has long served as fodder for heated debates on punctuation and grammar. Oxford comma advocates argue the punctuation mark provides clarity and avoids confusion. Detractors say the conjunction serves as enough of a delineation between items, and if the lack of a comma causes that much confusion, the sentence should just be written with more clarity.

Serial comma opponents would write the above sentence as “He bought milk, toast and eggs.” Proponents of the serial comma would argue that while that might not seem unclear, it would cause problems in a sentence like, “He brought his parents, Bill and Sue.”

Are his parents named Bill and Sue? Are Bill and Sue two entirely different people he brought along with his parents?

In the Oakhurst labor dispute, much of the focus is on a sentence in state law that describes how workers aren’t eligible for overtime pay if they’re involved in “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.”

Note, there’s no serial comma between “shipment” and “or.”

The question this ruling hinged on: Is “packing for shipment or distribution” a single overtime-exempt activity, or are “packing for shipment” and “distribution” two distinct activities that are both exempt?

The drivers read the passage to say that people who take part in packing for either shipment or distribution are exempt. Distribution wasn’t its own category as written, and because drivers don’t do any packing for either of those purposes, the law doesn’t apply to them, the drivers argued. Also, if “distribution” was meant to be its own exempt activity, why isn’t it written as a gerund (word ending in “-ing”) like all the other activities in the list?

When the district court originally ruled in favor of Oakhurst, it argued the law was clearly intended to count distribution as a distinct, exempt activity, meaning the drivers had no legal right to overtime wages.

The appeals court’s decision disagrees, arguing that the passage is too ambiguous, so the state’s wage laws must be “construed liberally” by the courts, giving more credence to the drivers’ interpretation of the passage.

In effect, a federal court ruling was overturned because of a poorly written sentence and a missing comma. Still, there’s good reason the state left out that comma. The Maine Legislative Drafting Manual states that, when drafting a law, “don’t use a comma between the penultimate and last item in a series.”

The sentence could have been made more clear if items were rearranged as “storing, distribution or packing for shipment of […],” if that was the law’s intention, in order to avoid the forbidden Oxford comma.

With the appeals court’s decision to overturn, the case likely will see future court proceedings before the lawsuit is ultimately decided.

BDN reporter Darren Fishell contributed to this story.

Follow Nick McCrea on Twitter at @nmccrea213.