Public defender Michael McCarthy told the justices that while Harris should still be charged with theft, he shouldn't be punished as if he had stolen a car. A riding mower is many things, a modern mechanical marvel among them, but McCarthy said it's not a motor vehicle under state law.
Prosecutors countered that the state defines a "motor vehicle" as a "self-propelled" device, and there's no doubt a riding mower meets that standard.
The state's top court agreed, concluding in an 18-page decision that the sentence should be overturned because the purpose of a riding mower is to cut grass, not transport people.
"To be sure, a riding lawn mower is capable of transporting people or property and of driving on the street for short stretches," Justice David Nahmias wrote in the opinion. "But that is not what the machine is designed for or how it is normally used."
In a dissent, Justice Harold Melton argued that Georgia lawmakers specifically defined "motor vehicle" broadly enough to include riding mowers. It warned that the ruling "has interpreted the statute in a manner that creates conflict and leads to an absurd result."
The case, which lawyers said set a precedent in Georgia, comes as other courts around the country grapple with similar concerns about whether riding lawnmowers and similar devices should be classified as vehicles.
There was no discussion in the ruling over how the state defines motor vehicles for the purpose of alcohol-related arrests.
That's still a blurry issue in Georgia, where it's a criminal offense to operate a car, truck or other "motor vehicle" while under the influence of alcohol. Despite the Supreme Court's ruling, prosecutors might still pursue charges against those driving under the influence on mowers, too.
That issue also has drawn headlines across the country, as prosecutors from West Virginia to Oregon have charged suspects with driving under the influence after catching them prowling the streets on lawnmowers, golf carts and even a tricycle.