The Association of Garda Sergeants and Inspectors said Martin Callinan's treatment of whistleblowers did not “sit easy” with the organisation.
Following the Commissioner's resignation earlier today, General Secretary John Redmond said "people should be free to make well-founded allegations."
"When they feel they need to bring it to somebody's knowledge, that should be a cast-iron guarantee that that's ok."
Anything that creates a perception that such an action isn't acceptable doesn't sit easy with us as an association … certainly not."
Redmond also said it is now time to look at a new policing authority, and a new authority board responsible for appointing senior gardaí is worth considering.
"I'd certainly welcome a discussion on it," he said.
"The idea that three or four names would go down and the Government would make an appointment based [on that].
"There's the Public Service appointments commission, where everybody has to undergo a rigorous selection process. Why should this be any different?"