Former garda press officer Supt David Taylor's account of his dealings with journalists was "unworthy of trust", a barrister representing RTÉ has told the Charleton tribunal.
The tribunal is hearing final submissions from legal teams before the chairman, Mr Justice Peter Charleton, writes his report into whether senior garda officers conducted a smear campaign against whistleblower Sgt Maurice McCabe.
Journalists John Burke and Paul Reynolds had reputations built up over decades, and there was "simply no evidence to support adverse findings against them", Sean Gillane SC said on behalf of RTÉ.
Both journalists deny allegations by Supt Taylor that he negatively briefed them about Sgt McCabe.
Mr Gillane said nobody had pointed to a syllable of Mr Burke's journalism to suggest he was party to any alleged smear campaign of Sgt McCabe, and reports by Mr Reynolds about Sgt McCabe were "a textbook example of journalism at work".
Mr Gillane said that email records showed that there were extensive editorial discussions before broadcast about the contents of news reports Mr Reynolds made on a leaked copy of the findings of the O'Higgins commission of investigation.
The O'Higgins commission looked at complaints made by Sgt McCabe about policing in the Cavan-Monaghan district. Mr Gillane submitted that there was no evidence of any external interference or briefings in relation to the reports from Garda HQ.
Mr Gillane also said there was no reason why journalist Philip Boucher-Hayes would make up an encounter with former commissioner Martin Callinan. The journalist said that before a Crimeline programme in December 2013, Mr Callinan told him Sgt McCabe had done "the worst kind of things".
Counsel said that Mr Boucher-Hayes had volunteered his evidence after the chairman called on anyone with information to come forward, and had reported to colleagues what Mr Callinan had told him shortly after the event occurred.
Earlier, Darren Lehane BL said that the meeting between Mr Boucher-Hayes and Mr Callinan was relevant to his client, John McGuinness TD, as it showed a pattern of behaviour.
Mr Lehane said the tribunal chairman was entitled to consider the evidence of other witnesses about encounters they had with Mr Callinan on January 24, 2014. In particular, Mr Lehane referred to a brief meeting between Mr Callinan and comptroller and auditor general Seamus McCarthy.
Mr McGuiness told the tribunal that on January 23, 2014, after a Public Accounts Committee (PAC) meeting, Mr Callinan told him Sgt McCabe "fiddles with kids”. Mr McGuiness said that at a meeting in a Dublin hotel car park the following day, Mr Callinan also said that there were investigations into abuse allegations against Sgt McCabe.
Mr Lehane said that the fact that similar remarks were reported by Seamus McCarthy, the comptroller and auditor general, showed a pattern of behaviour by Mr Callinan.
Mr Callinan was "desperate" to stop Sgt McCabe appearing before the PAC, Mr Lehane said. He submitted his client, Mr McGuinness's, evidence was supported by a near-contemporaneous note he made after the meeting, and by similar accounts of meetings given by other witnesses.
The barrister said that Mr Callinan's claims that two witnesses would raise the same issue in an identical manner, that he would respond in a near identical manner, and never make a record of those "unusual" conversations anywhere were not credible.
Mr Lehane said his other client, journalist Ann Harris, was subjected to attacks on her character and threatened with defamation proceedings and suggestions she was motivated by bitterness or a grudge.
Michael O'Higgins SC, on behalf of Supt David Taylor, said that of 12 journalists his client had nominated who would support his evidence, 10 had "confirmed in stark terms they did not receive any such briefings, and two of the journalists weren't willing to comment."
Supt Taylor claims that he was directed to negatively brief journalists about Sgt McCabe by Commissioner Callinan, and that his deputy Nóirín O'Sullivan was aware of the direction. Both former commissioners deny the allegations.
Mr O'Higgins said that it was either "an incredible coincidence" or there was something to Supt Taylor's evidence, as it matched closely the evidence of other witnesses about what they alleged Mr Callinan said to them.
"If he was a fantasist who just wanted to throw a spanner in the works, he was a very fortunate fantasist and he was a very lucky spanner thrower," Mr O'Higgins said.
Mr O'Higgins said that the tribunal could conclude that Supt Taylor and Mr Callinan "were working in tandem, rather than separately and in ignorance of each other”. He said that Supt Taylor did "bear an animus" to Ms O'Sullivan, and had incorrectly believed she was a driving force behind his arrest and attempts to discredit him during an investigation into garda leaks.
Mr O'Higgins said that Supt Taylor's evidence was capable of being believed, and it was up to the chairman to decide if it should be believed.
The tribunal continues this afternoon.