"As a senior officer in the District, he should not have used his position to influence the decision-making of other officers," Judge Doherty said.
"His actions were inappropriate and improper."
Judge Doherty told the Herald that as far as he was aware, the senior officer remained with the police.
He said a senior officer would mean an officer of the senior sergeant rank or above, but referred further questions on the officer and any disciplinary action to police.
A police spokeswoman later confirmed the man remained a police employee.
Police are refusing to say what disciplinary action, if any, he faced.
"As per your first two questions, please note - the New Zealand Police has the same privacy obligations when it comes to employment matters as any other employer, and as such, we are not in a position to provide any information."
The saga began when the man who would go on to be charged, dubbed "Mr X" in the IPCA's report, became involved in an argument with another man outside a bar in Vine St, Whāngārei.
X threw a punch which hit the other man's girlfriend, who then complained to police.
He was arrested and charged.
After his first appearance in the Whangarei District Court, X talked about his arrest with his father, called Mr Y in the report.
The senior officer and Y had a business relationship and knew each other personally.
Y was concerned his son was having difficulty contacting police regarding CCTV footage he believed would vindicate him, and contacted the senior officer directly.
The senior officer then become involved in the case and the IPCA found he advised the father that his son should not make a statement to police.
He went on to improperly engage with various officers to ensure the prosecution of X did not progress, the IPCA found.
Text messages obtained by the IPCA revealed continuing collusion between the senior officer and the charged man's father.
The father texted the senior officer to ask it was proving a "mission" to bring his son's case forward.
The senior officer replied:
"It is but I've been watching Mission Impossible, if they can do it, so can you and me"
In addition to advising X not to make a statement to police, the IPCA found he allowed the father and son into a police station to view the footage, against normal practice.
He also advised another officer that X was a "good kid" and "deliberately but erroneously impugned" the credibility of the woman who complained of being punched.
The senior officer went as far as to tell an officer to call the complainant and tell her there was "little evidence of an assault", the IPCA report said.
However, the IPCA conducted its own analysis of the footage, finding it clearly showed X throwing a punch after the complainant moved between X and her boyfriend.
The report found the CCTV analysis of the police prosecutor who withdrew the charge was flawed and his decision-making was improperly influenced by the senior officer.
The IPCA also found the senior officer breached the conflict of interest policy and should have referred Y to another officer to address his concerns.
