Despite the court ruling, police said they would still charge users who did not have their Segways registered and licensed because, under the Land Transport Act 1998, they were classified as vehicles, not mobility devices.
But Mr Summers welcomed the court's decision, saying it was good for all Segway users.
"I am glad that I proved people can use Segways as a mobility device," he said.
Police will not appeal the judgment.
Police road policing manager in Northland, Inspector Murray Hodgson, said riders of any transportation devices, irrespective of whether they needed to be licensed or registered, could be charged or warned if they became a "criminal nuisance" to other motorists on the road or a footpath.
"Where there's confusion in terms of vehicle specifications and requirements, we seek legal advice. We don't readily go ahead and charge someone," he said.
Judge Maude rejected the Crown's submission that although a Segway could be adapted for use by persons requiring mobility assistance, it was not designed and constructed for that purpose.
On the balance of probabilities, he said, Mr Summers' Segway was designed and constructed for use by those who required mobility assistance due to a physical or neurological impairment.
"It is not possible, or necessary, for me to determine whether all Segways comply with the (Section 2 of the Land Transport Act 1998) mobility device exemption," Judge Maude ruled.
Segway New Zealand managing director Philip Bendall described the court ruling as a "sensible" outcome as Segways could not be regulated under any motor vehicle category.
Mr Bendall said Segways were used in all but two or three States in the US, most of Europe and in Queensland.