Colin Webster was convicted of behaving in a disorderly manner and assaulting a police officer in the execution of duty but after an appeal both convictions were dropped.
Justice Matthew Palmer made the judgment on Webster's appeal today in the High Court of New Zealand, finding a miscarriage of justice took place.
In August 2008, Webster called police for assistance at his Manurewa home because of an altercation with his methamphetamine-addicted son.
"Webster was highly agitated and holding a metal pole a short distance from his son when the Police arrived," Palmer's summary said.
"The two constables did not know quite what the situation was.
"One entered his property, without permission, to ask questions and Webster pushed him away."
Webster pleaded guilty to behaving in a disorderly matter after being charged with the offence but pleaded not guilty to a charge of assaulting a police officer in the execution of his duty and possession of an offensive weapon.
However, he was convicted after a trial - a decision Webster appealed.
Palmer said the judgment under appeal did not identify the lawfulness of the constable's presence on Webster's property.
"I do not consider the constable was lawfully on the property and, therefore, he was not in the execution of his duty," he said.
"Neither did the judgment under appeal identify the legal definition of an offensive weapon or provide any reasoning about whether its possession was proved.
"I do not consider the evidence sustains, beyond a reasonable doubt, that the metal pole was intended by Webster for the use of causing bodily injury or that he had no reasonable excuse to hold it."
In response to his findings, Justice Palmer said a miscarriage of justice had taken place and quashed both of Webster's convictions.