However Culpan will still be called as a witness and cross-examined as the case against the police now reaches a judge-alone trial, which began yesterday before Justice Timothy Brewer in the High Court at Auckland.
Opai, now a police file management support officer, alleged that Culpan's comments were false, tarnished her reputation, ostracised her from colleagues, and prevented promotion.
She claims police breached the Bill of Rights, principles of natural justice, and code of conduct under the Policing Act.
She has also accused several senior police officers of misleading the courts, engaging in retaliatory conduct, and being "members of an old boys' club".
The police's defence, led by Matthew McClelland, QC, denies that the comments were defamatory and argues the remarks were published on occasions of qualified privilege and were not serious enough to engage in a defamation proceeding.
Opai alleges that in the performance review, Culpan made defamatory comments.
Although the overall nature of the appraisal was positive, Opai took exception to a passage which said her "sense of responsibility can be misdirected and be viewed by other[s] as malevolence, or ill will".
The internal briefing paper was also written by Culpan as part of a staffing review.
Opai alleges several parts of the paper were defamatory. These outlined differing management styles between watch-house officers that were causing poor communication and disruption.
"The root cause of this tension appears to have been through a power struggle by some supervisors, a void leadership and management from the previous O/C Station, and a truncated investigation into two employment complaints," the paper reads.
The complaint form, authored by Culpan, was made after apparent discrepancies were discovered in the timesheets for Opai and her staff.
Culpan was concerned staff were leaving work early but were still claiming a full day's pay.
The report was titled "Melissa Opai: Breach of the Code of Conduct", and read: "It would appear that these issues have reached a tipping point.
"It is my opinion that if the staff named in the email/complaint have left early without correctly filling out timesheets, it will have been sanctioned by Miss Opai although I have not traversed this point with those identified," Culpan wrote.
"I believe these actions fall under the general headings of Honesty and Integrity and dependent upon interview with Miss Opai, may be viewed as misconduct in that they represent repeated absence from duty or place of work without proper reason or authorisation."
Opai said the report implied she was dishonest, a hypocrite, lacked integrity, and there were grounds justifying an employment inquiry.
She had also made a complaint in 2013 against a colleague for similar behaviour.
Opai claimed two particular diary entries of Culpan's, which noted Opai's performance during the past year and were handed to his successor in 2014, were defamatory.
One entry discussed a complaint Opai had made, which was described as an attempt to "scuttle [two persons'] police enrolements", and the other about timekeeping complaints.
During his opening address today, Opai's counsel, Neville Woods, said Culpan's comments had resulted in his client being overlooked for promotion and demoted.
Woods said the performance appraisal was "false" and had contributed to Opai being ostracised from her work colleagues at the direction of management.
Opai had also suffered physical and emotional stress-related issues as a result of the dispute, Woods told the court.
In court documents, both Culpan and police have said all of the comments were made solely in the performance of Culpan's workplace duties and read by people as part of their work duties.
The case was transferred to the High Court from the Employment Court due to the amount of compensation sought.
An earlier version of this story incorrectly referred to Culpan as a party to the proceedings this week in the High Court. A case against Culpan has already been dismissed by the High Court.
