The Disclosures Tribunal has heard that Sergeant Maurice McCabe's background, including a previously dismissed allegation of sexual assault, were discussed during a legal consultation prior to the O'Higgins Commission.
An Garda Síochána’s head of legal affairs told the tribunal that the discussion was inconsistent with former garda commissioner Nóirín O’Sullivan's policy of supporting the whistleblower.
The inquiry is examining whether Ms O'Sullivan inappropriately relied on unjustified grounds to discredit Sgt McCabe at the O'Higgins Commission.
In the months prior to that inquiry's hearings, several meetings had been held with Sgt McCabe to tackle workplace issues and Ms O'Sullivan had been publicly supportive of him.
External mediator Kieran Mulvey had also been brought in.
On 11 May 2015, legal counsel for the garda commissioner at O'Higgins held a consultation to discuss the upcoming inquiry.
The meeting was told by Chief Superintendent Fergus Healy, the garda commissioner's liaison on O'Higgins, about the 2006 sexual assault allegation made against Sgt McCabe.
Supt Healy also told the meeting about Sgt McCabe's issues on bullying and harassment and a disagreement with a colleague where Sgt McCabe had alleged false imprisonment.
Counsel for the tribunal said this appeared to question Sgt McCabe's motivation in bringing the complaints being examined by O'Higgins.
Patrick Marrinan SC said the assault allegation was history which had nothing to do with the complaints and it was peculiar that it had been mentioned.
Ken Ruane, An Garda Síochána's head of legal affairs, also attended the meeting.
He told the Tribunal that the discussions on Sgt McCabe's background were "inconsistent" with the garda commissioner's policy on Sgt McCabe and he said that he could not see how a "reaching out" to the sergeant in the months prior to O'Higgins, could continue.
Sgt McCabe's lawyer Michael McDowell said it flew in the face of what the garda commissioner was doing on paper.
Mr Justice Peter Charleton said it was hard to understand what the background discussion had to do with the O'Higgins Commission.
He said some of the history seemed to be related to Sgt McCabe's temperament and character and could indicate that he was a bitter man.
Mr Ruane also said the meeting of 11 May did not confirm that counsel for the garda commissioner should call in to question Sgt McCabe's motivation.
He got a phone call from Annmarie Ryan of the Chief State Solicitor's office at 11pm on Saturday 16 May 2015 telling him of a row at O'Higgins the previous day when counsel for the commissioner had challenged Sgt McCabe's motivation.
Mr Ruane said he did not know what had happened between 11 and 15 May to change tack at the O'Higgins Commission.
Ms Ryan told the Tribunal that she did not receive any instructions from or have any contact with Ms O'Sullivan in the days leading up to the Commission.
She said she did not know who had provided the background information during the meeting.
Ms Ryan said she had insisted on the presence of Chief Superintendent Healy at the O'Higgins Commission as a representative for the garda commissioner.
She said that, in the period before the Commission opened, she had no direct contact with the garda commissioner and all contact was through Chief Superintendent Healy.
Ms Ryan told the Tribunal that, in the days before the Commission held its first sitting, barristers for the commissioner met with garda witnesses.
In her statement, she said that "following consultations with all witnesses, counsel advised that Sgt McCabe should be challenged on his motivation in making numerous complaints of serious corruption against several senior officers.
Ms Ryan is due to continue giving evidence when the Tribunal resumes on Wednesday morning.