Ms Coy raised many complaints dating over several years, the court found that she only formally raised a personal grievance on December 22, 2002, so only events in the preceding 90 days could be considered.
The court noted the case raised the "arguable inadequacy" of the law when a complaint is about ongoing historic incidents.
Discussion of earlier events was allowed to be treated as background evidence, but the case rested on three grievances within the time frame.
In the first, Ms Coy decided not to charge the victim of an assault for driving offences, despite being told to by her supervising officer, Sergeant Glen Smith.
The incident resulted in a note about her performance being placed on a shared computer folder where other staff could read it.
She was also reported for failing to promptly dispose of a "bullet" of cannabis that had been handed in by a member of the public.
These incidents resulted in her being sanctioned and placed on restricted duties.
The second grievance related to her movements being restricted while on duty, preventing her from returning home during meal breaks, as she had done previously.
The claim of unjustified dismissal arose from a series of events during an extended period of stress leave that ultimately lead to her resigning from the police.
During this time police also made the "ill-considered, over-reactive" decision to remove her station keys, effectively locking her out of the workplace.
The police commissioned an independent report into dysfunction at the Temuka station, but Ms Coy felt the findings demonised her and painted her as the problem.
Judge Colgan found that Sergeant Smith had been at times been "motivated by a wish to minimise or conceal his own managerial shortcomings and performance failings, but did not have a deliberate motive to end her career".
"Although at times Sergeant Smith made life difficult for the plaintiff and, on occasions, did so unlawfully, I am not satisfied on balance that this was coercion by the sergeant with the deliberate and dominant purpose of bringing about her disengagement from the Police as occurred."
The Court found that Ms Coy had not been unjustifiably dismissed, but had been unjustifiably disadvantaged in her employment.
The parties were to reach agreement on compensation by negotiation or mediation.
The Court also apologised for the long delays in the case, which were caused by several factors, including the Christchurch earthquakes.
