Prior, fearing that the man had snatched pictures of his own children that he had on his phone, returned to the house.
Defence counsel Jonathan Eaton said Prior allegedly reached through a gate and grabbed the man by his scruff of the neck and demanded to know what photographs he had taken.
Mr Eaton said the alleged assault was so minor that if his client was not a serving police officer, it would never have reached court.
The lawyer said that since it was his client's personal cellphone, also used for Police Association work, it contained personal, private and privileged information, including pictures and details of his children.
The facts were not disputed, he said, and asked Judge Paul Kellar for the case to be adjourned until April 2 for his client to be considered for diversion. Since he was a serving police officer, diversion would have to be considered by the Commissioner of Police, Mr Eaton said.
The Commissioner will now consider whether diversion - the scheme for first-time offenders where a criminal conviction can be escaped if they apologise - is an appropriate outcome for Prior.
Mr Eaton said that if diversion was not granted, he would apply for a discharge without conviction.
Judge Kellar recorded the guilty plea but did not enter a conviction.
Prior was remanded at large, while his lawyer did not seek a continuation of the interim name suppression order.
Through his work as Police Association Canterbury branch director, Prior is highly popular with local front-line officers.
One officer, who did not wish to be named, said all of the rank and file knew of the incident and was surprised it had made it to court.
"Craig's a great guy and doesn't deserve to be hung out to dry,'' the officer said.
"I hope there's a positive outcome from all of this.''
Police Association president Greg O'Connor said Prior had "voluntarily'' stood down from his Association role while the court case was ongoing.
His work answerphone today directed enquiries to Association colleagues, while the national website listed him as "currently unavailable''.
In the meantime, Prior - who is also a police search and rescue coordinator - has the backing of the Association.
"Officers on duty, dealing with matters that arise out of their duty, get the support of the Police Association,'' Mr O'Connor said.
A police spokesman confirmed that Prior is currently suspended on full pay while court proceedings are live.
District Commander Superintendent Gary Knowles says police will continue to deal with the matter internally.
Last month, an Employment Relations Authority judgment ruled that a long-serving Canterbury officer was justifiably dismissed after he used excessive force on a drunk nightclubber who snatched his police hat.
Nearly 70 New Zealand police staff have been arrested in the past three years.
Charges includes assault, drug dealing, drink-driving and theft.
National manager of professional standards Detective Superintendent Sue Schwalger said police take a zero-tolerance approach to criminal behaviour in their ranks.
