Mr Ramkissoon is seeking compensation and reinstatement as a sergeant.
Earlier this year the defendant - the Commissioner of New Zealand Police - asked the Employment Court for a ruling on what issues and evidence could be raised during next week's hearing.
In his interlocutory judgment issued last week, the Chief Judge of the Employment Court, Graeme Colgan, said Mr Ramkissoon witnessed an incident in the Whakatane police station cells in October 2006 which resulted in four Whakatane police officers being charged with assaulting a prisoner.
They were acquitted after a trial in 2008, during which Mr Ramkissoon gave evidence.
"Counsel for the plaintiff [Mr Ramkissoon] asserts he has always maintained that the 'Whakatane four' incident was a significant turning point in his career and that it was the start of criticisms of him and allegations against him by senior officers," the judgment states.
However Edrick Child, the Commissioner's lawyer, said the "Whakatane four" incident was not mentioned in Mr Ramkissoon's grievances with his employer or in previous court pleadings. Mr Child said the first grievance was raised about 13 months after the assault trial concluded.
Judge Colgan ruled the "Whakatane four" incident "can play no more than a background role in the establishment by Mr Ramkissoon of his personal grievances".
The hearing starts Monday and is set down for seven days.