The Chair of the Policing Authority says they are limited in what they can ask about the alleged campaign to discredit Sergeant Maurice McCabe.
The Garda Commissioner and her highest ranking colleagues have been questioned by the Policing Authority in Dublin today.
Commissioner Noirin O’Sullivan said she welcomed that the Charleton Inquiry into the McCabe affair would be held in public.
Chair of the Policing Authority is Josephine Feehily: "We are mindful that there are a range of questions which the authority might like to ask, and no doubt, questions which the public would like to see asked and would like answers to.
"However, as a matter of course, we are not in a position to discuss in public the specifics of any open investigation, whether criminal or internal, or any civil litigation. This is also the case in relation to matters which are subject to a Tribunal inquiry."
Garda chief Noirin O'Sullivan has admitted she is worried confidence in the force is taking a battering amid a welter of controversies.
Under cross-examination by one of the force's official watchdogs, the commissioner said it will take some time to uncover the full impact of ongoing scandals.
"Am I concerned about any impact on confidence? Of course I am," she told the Policing Authority during a public meeting in Dublin.
Ms O'Sullivan also accepted relentless negative revelations swirling around the force, in the media and in public commentary, were taking their toll on her rank and file.
"Of course it has an impact," she said.
"There is no doubt about it, it will take some time to see what the impact on confidence is.
"I think we have to work really hard to reassure people that the day job is continuing to be done and we are there for people in their times of need."