The Government has asked Circuit Court Judge Brian Curtin for an explanation, by next Tuesday, of his apparent downloading of child pornography from a website.
The Taoiseach, Mr Ahern, also said the Oireachtas might have to deal with the possible removal of the judge from office.
And he told the Dáil that the Government has asked the Director of Public Prosecutions and the Garda Commissioner for reports about the circumstances of the collapse last week of the trial of the judge on child pornography charges.
He promised that he would make the contents of these two reports known "in some form".
A subdued Dáil heard the Taoiseach say that in accordance with Constitutional provisions, "the houses of the Oireachtas can, where there is stated misbehaviour, remove a judge from office. That is a decision which the House could have to address in the near future.
"If there are grounds for stated misbehaviour, the removal from office - this is the only option. There are no alternatives. Moreover monetary compensation simply does not arise. There is no provision for this and no justification for it on such removal."
The Labour leader, Mr Pat Rabbitte, asked why the Taoiseach explicitly said there would be no monetary compensation. "Is he saying that if there were an offer of resignation here that there would be no question of any compensation for loss of office?" Mr Rabbitte asked.
The Taoiseach replied that "what I stated earlier is the Government's view on the matter".
Before the Taoiseach addressed the Dáil, the Ceann Comhairle, Dr Rory O'Hanlon, reminded TDs that as "this House may ultimately have to adjudicate on this matter", they should refrain from making references that could be prejudicial.
Mr Ahern said the Government was making the request of Judge Curtin with a "view to shortly making a fair and objective assessment as to whether grounds exist for a motion of removal from office for stated misbehaviour".
The Fine Gael leader, Mr Enda Kenny, said there was "concern about the return of Judge Curtin and the possibility of his return to the bench".
Outlining why the Government had written to Judge Curtin, Mr Ahern said that the underlying factual basis for the application for a search warrant and for the preferring of charges were not heard in evidence.
"Judge Curtin did not give or adduce evidence on his own behalf in response to the charges preferred against him because of the course of that trial proceeding.
"In these special circumstances and bearing in mind the seriousness of the charges against him, the Government decided to write to Judge Curtin in order to seek an explanation from him of the circumstances of his apparent access to a website and downloading of child pornography images from same."
Mr Kenny asked if there was any concerns about his "conduct or activities" before his appointment, to question his suitability for the position.
Mr Ahern said he was not aware of any issue around Judge Curtin before his appointment but he would have to do an indepth check to answer that completely.
Mr Rabbitte said he remembered "times when a letter going missing was enough to send the opposition spokesman for justice at the time on a rampage". He asked why the Judicial Conduct and Ethics Bill, first promised in 2002, was not yet before the House.
The Taoiseach said the process for the appointment of the judiciary had changed substantially and it appeared to work very well in the normal course of events but the Bill was an issue outstanding. If it was necessary the Government would have to enact it, but it might not be.
