Chair of the Police Federation for Northern Ireland Liam Kelly has said that PSNI Chief Constable Simon Byrne's position had become 'untenable'.
Mr Byrne tendered his resignation following a series of controversies, including a major data leak and the unlawful disciplining of two junior officers.
The announcement by the Northern Ireland Policing Board came weeks after the police force accidentally shared the names and work locations of every member of staff in a major data breach.
The surnames, initials, work location and department of each staff member were included in error in response to a freedom of information request.
Mr Byrne faced additional pressure after court last week found he had unlawfully disciplined two junior officers who arrested a victim of a 1992 sectarian shooting in Belfast, while policing a wreath-laying event to mark the anniversary of the attack.
Mr Justice Scoffield said he was persuaded the officers were disciplined to avoid republicans withdrawing their support for the police force.
Liam Kelly, chair of the Police Federation for Northern Ireland, a representative body for officers, says the Chief Constable's position became questionable and then untenable.
"The Ormeau Rd Judicial Review and the shocking potential course of action following the Policing Board was the final straw for Mr Byrne," Mr Kelly said.
"The ruling was damning, and his initial acceptance followed by a volte face around a potential legal appeal grievously undermined his credibility and authority to lead the PSNI.
"It called into question his judgement, decision-making abilities and made his position untenable.
"Mr Byrne has now done the right thing. It is clear now that a full investigation is required into these matters to determine whether anyone else should be held to account for this fiasco for policing."
Mr Kelly said morale has never been lower in the police service.
"On a personal level, Mr Byrne has always been approachable and courteous," he added.
"He has provided over 40 years of policing service to the communities across the United Kingdom."
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The Democratic Unionist Party last week called for Mr Byrne's resignation.
DUP Leader Jeffrey Donaldson has said Mr Byrne's resignation is the first step towards rebuilding confidence in the PSNI both inside and outside the organisation.
Speaking from Westminster he said: "We welcome the decision by the Chief Constable to step down.
"It is the right thing to do following last week's ruling by Mr Justice Schofield that the PSNI senior command unlawfully disciplined two of its own officers to appease Sinn Féin.
"The focus now must be on the future of policing in Northern Ireland and ensuring we have efficient, effective policing which everyone can have confidence is impartial in its actions."
SDLP leader Colum Eastwood said confidence in Mr Byrne as chief constable had been "irreparably shattered".
He said: "Policing in Northern Ireland is in a very difficult place right now.
"Successive crises have left confidence in the chief constable shattered from all directions.
"His resignation today was the right thing to do and was necessary to begin to address the serious issues facing the PSNI.
"Over the last month our primary interest has been safeguarding and supporting officers put at risk by the data breach.
"Now it must move to saving the new beginning to policing that so many took risks to secure.
"That includes addressing significant concerns about the erosion of confidence in the Policing Board as the body charged with holding the PSNI to account."
Northern Ireland Secretary Chris Heaton-Harris has thanked Mr Byrne for his work and said he would liaise with the PSNI as a successor was appointed.
Answering a question from the DUP leader Jeffrey Donaldson, Mr Heaton-Harris said: "He will know that the appointment of a new chief constable is a matter for the Northern Ireland Policing Board and I will continue to liaise with the senior management of PSNI whilst the process of appointing a successor gets under way."
