The Greens contend Mr Ryan is entitled to be included in the debate, involving seven party leaders, due to be broadcast on Monday next.
RTÉ’s rule that only registered political parties with three elected TDs can participate in such debates is unlawful, unfair, overly rigid and breaches democratic values and RTÉ’s public service obligations, it is claimed.
The station’s decision fails to take into account the Green Party has a similar level of support to some of the other parties taking part in the debate, the Greens’ also claim.
The proceedings have been brought by Green Party trustee Tom Kivlehan, a former councillor with the party, who said the case was about “democracy” and the entitlement of the Irish people to hear the views of all parties.
The party secured leave on Friday last to serve short notice of the proceedings on RTÉ and the matter was returned before Mr Justice Noonan yesterday.
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Siobhan Phelan SC, for the Greens, said she was anxious to secure a hearing this week.
Nuala Butler SC, for RTÉ, said her side would be ready for a full hearing this week.
After making directions for exchange of legal documents between the sides, the judge fixed the case for hearing on Thursday.
Mr Kivlehan and Green Party deputy leader Catherine Martin were in court for the brief mention of the proceedings.
The Green Party had complained to the Broadcasting Complaints Commission but were advised the BCC’s Compliance Committee was limited to dealing with complaints arising from programmes already broadcast.