RTÉ defamation case: Claire Byrne thought Joe Costello had gone 'doolally' on radio show

Ms Byrne thought claims by Joe Costello that Sinn Féin political manager Nicky Kehoe was a member of the IRA army council controlling how councillors voted at meetings were outrageous.

She said her tone towards Mr Costello, then a Labour TD and a former Minister for Trade and Development was incredulous.

"I thought he had gone doolally.

"I remember sitting there thinking where is this coming from.

"I expected him to represent government policy and what he was doing was bringing it down to local politics.

"My tone was incredulous because that is how I felt at the time."

She was giving evidence as part of RTÉ's defence of a defamation action against it by Mr Kehoe, a former city councillor and Sinn Féin director of elections and now employed as a political manager by the party.

He says he was falsely described by Mr Costello, on an October 2015 "Saturday with Claire Byrne" live panel radio programme, as a former chief of staff of the IRA who was controlling how Sinn Féin councillors on Dublin City Council vote.

Mr Kehoe's case ended on Friday following further cross-examination of Mr Kehoe and evidence from three community activists in Mr Kehoe's Cabra area who all said they did not believe his (Kehoe's) standing in the community had changed as a result of what was said on the programme.

In her evidence, which began on Friday afternoon, Ms Byrne said after Mr Costello made the comments, her producer, Kay Sheehy pressed the "talk back button" which allowed the producer talk to her. The talkback button is a warning system between presenter and producer and a click came on in Ms Byrne's headphones.

She thought what Mr Costello had said was outrageous and strange and she was about to intervene when another panellist, Sinn Féin's Eoin O'Broin, spoke and named Mr Kehoe.

Before that, she did not know who Mr Costello was talking about.

Asked by her counsel Cian Ferriter about a suggestion from Mr Kehoe, during his evidence, that she should have cut Mr O'Broin off from naming him again, she said she felt if she had stopped Mr O'Broin she would have been doing him (O'Broin) and Sinn Féin a disservice.

She said Mr O'Broin, who she earlier described as a very smart and intelligent person and one of Sinn Féin's three top people, stepped in to defend Mr Kehoe and proceeded to dismantle Mr Costello's argument.

"In my professional opinion, I felt in a live broadcast if I had stopped him from proceeding with that defence that would have caused more harm."

She felt Mr O'Broin had, from the minute he intervened, destroyed Mr Costello's argument.

RTÉ guidelines are that presenters must act promptly when issues like this occur. While this was quite an unusual instance, she had in the past stopped people from naming others during discussions and saw that as her professional duty.

In relation to a clarification issued at the end of the programme, which Mr Kehoe had described as "very watery", Ms Byrne said this was done at the end rather than shortly after it occurred because if she had done it earlier there was a risk of Mr Costello "coming in and saying something else".

"I decided to move on and let us all come back with cool heads at the end of the programme and issue the clarification".

The case, which is being heard before a judge and jury, continues on Tuesday.