The Independent Police Conduct Authority says police trespassed by going on to a man's property even though he had a Keep Out Private Property sign, when they were trying to deliver court documents.
Police went to the Canterbury property in December 2020 to serve Family Court documents, on the court's behalf, to the man's then partner.
Neither the man nor his partner were home, and police spoke briefly to a young person before leaving.
Following the visit, the man complained that police could not enter his property because he had revoked the implied licence enabling any person, including police officers, to enter private property to communicate with an occupier.
The IPCA said an occupier can terminate or limit the implied licence to enter and remain on private property through direct communication or unambiguous signage.
The man complained that the officers should not have entered his property because he had the private property sign up and in August had emailed the Canterbury district commander saying police could not enter his property.
The authority found that "the service of originating proceedings and a judge's minute notifying of an upcoming conference is not the execution of a court process pursuant to a court order".
It said police officers cannot be regarded as court officers for this purpose, and if the issue was urgent then there should have been an application for substituted service.
The authority said the Keep Out sign was prominent and unequivocal signage which revoked the implied licence allowing entry, and the two officers' actions constituted a civil trespass.
Canterbury District Commander Superintendent Tony Hill said police acknowledged the IPCA's report found the officers' actions constituted civil trespass.
He said the report noted it was unclear whether the officers knew about the man's August email saying police were not to enter the property.
Hill said police worked incredibly hard to uphold the law.
The officers involved went onto the property in good faith and left after being told the person they sought was not there, he said.