The study by the Campaign Against the EU Constitution (CAEUC), claims 63% of the contributors to RTÉ news items focused on the Lisbon treaty were supporting a yes vote.
Three television programmes (Six One News, Nine News and Questions & Answers) and three radio programmes (Morning Ireland, News At One and Drivetime News) were analysed via RTÉ’s website from January 1 to June 14, 2008.
The study found that out of 510 contributors to these programmes, 320 (63%) favoured a yes vote, while 190 (37%) favoured a no vote.
The research, which runs to more than 70 pages, outlines 115 incidents which the CAEUC claims people advocating a no vote were treated unfavourably compared with those on the yes side.
The report alleges that much of RTÉ’s coverage of Lisbon was designed to highlight how the yes side could win rather than why the yes side should win.
The study was particularly critical of a Six One interview involving Richard Boyd Barrett of People Before Profit and former taoiseach Dr Garret FitzGerald of Fine Gael, where presenter Sharon Ní Bheoláin described Mr Barrett as a failed election candidate and asked why anyone should believe him over Dr FitzGerald.
The report accuses RTÉ of having framing the debate in terms of “How can the yes side win?” and not “Why should the yes side win?”
It claims many reports on the six broadcasts studied began and ended with the point of view of the yes side.
The report also says there was a failure by the station to question the assertions made by the yes side and that an editorial decision was made to incorrectly portray the no campaign as Euro-sceptic.
However, head of public policy at RTÉ Peter Feeney disputed the findings of the report.
“We would totally refute the findings of the report. It monitored six programmes whereas we monitored all our news and current affairs programmes and we feel overall we were pretty close to 50-50,” he said.
Mr Feeney said of the 205 principal interviewees across its coverage of the Lisbon treaty, 105 (52%) were from the yes side with 100 (48%) advocating a no vote.
Mr Feeney also pointed out that none of the complaints made to the Broadcasting Complaints Commission (BCC) citing a bias towards the yes side were upheld.
“There were 11 complaints made to the BCC about various aspects of the coverage of Lisbon. Ten of those related to bias towards the yes side. The BCC didn’t uphold any of them. So an independent, external body examined RTÉ’s output and said it was fair and impartial,” he said.