The High Court will deliver its judgment on Monday in a legal challenge by the Green Party against a decision by RTÉ not to invite it to take part in the televised leaders' debate.

Earlier, lawyers for RTÉ told the High Court it applied objective, impartial and transparent criteria for inclusion in the forthcoming political party leaders' debate.

The submission was made on the second day of an action by the Green Party against a decision by the broadcaster which excludes the Greens from the televised debate.

The Green Party was not invited to take part in the debate because it did not have any TDs in the outgoing Dáil.

Senior Counsel Nuala Butler told Ms Justice Marie Baker that the Greens had in previous years taken part in the leaders' debate under the same criteria and did so without objection.

She said now that the party could not meet the criteria it was a problem and allegedly unconstitutional.

She said the Greens were looking for subjective criteria to be applied this time and to have its position on environmental issues to be included in the debate.

Ms Butler said the Greens were proposing that the overall criteria applied to general election coverage be distilled into one particular programme which was "completely unworkable and not based on any constitutional principle".

She said the provisions of the Broadcasting Act which the Greens accused RTÉ of being in breach of also applied to all broadcasters, yet the Greens had not complained to TV3 or TG4 about being excluded from leaders' debates on those channels.

In its submissions to the court, RTÉ said the inclusion of all the leaders of all political parties irrespective of Dáil representation would be "unfeasibly large and seriously undermine" the merit of any TV leaders' debate.

It said fair and impartial broadcasting did not require that all possible political opinions and or policies and parties be given equal airtime in a leader's television debate.

The broadcaster said it was entitled to have regard to the increased number of political parties with significant Dáil representation and the necessity to transmit a coherent programme format.

It said the criteria complained of were matters of editorial judgment which were exercised in relation to the entirety of the General Election.

Ms Butler said the Greens seemed not to be making the case that all party leaders should be included, just that the Greens should be the eighth leader in Monday's debate.

"What they are really doing is not putting forward an alternative criteria but suggesting that the current criteria should not apply to them.

"RTÉ applied a criteria which it believes are objective and fair and deliberately did not enter into a subjective assessment of the worth or merit of a political party or their platforms," added Ms Butler.

In a sworn statement, RTÉ's Head of Current Affairs TV David Nally said the station was at all times conscious of the need to strike a reasonable balance between inclusiveness and the need to provide a coherent and worthwhile debate to viewers.

The threshold of three TDs ensured that all political parties with significant representation would be invited to attend and the number of invitees would not be excessive

He said the purpose of providing a televised leaders' debate was to provide the public with an informative and engaging debate with meaningful discussion of the issues of concern to the electorate.

He said the addition of speakers had an effect on the quality of the resulting debate and he would not be confident that a debate with eight speakers would be as coherent and informative as one with seven.

Mr Nally said there were complex editorial decisions to be made in the circumstances of any election and to suggest that a party or candidate who was not included in a particular programme had a legitimate complaint to take to the courts on the basis of unfairness would effectively result in the courts being asked to pick the members of current affairs panel discussions. This would be "manifestly absurd and unnecessary", he said.

Mr Nally said it was acknowledged that current Dáil representation may not be the perfect criterion for invitation to the party leader debate but it was objective and impartial.

He said the Greens had been invited to take part in other programmes' panel discussions and would also be included in other news and current affairs coverage during the election campaign.

Greens argue rule is 'unlawful'

Yesterday, representatives of the Green Party told the court that the rule is unlawful, unfair and overly rigid.

The party also argued the rule breaches democratic values and RTÉ's public service obligations.

Opening the case, senior counsel Siobhan Phelan said the decision would result in unfair coverage of pre-election policy, an inequality of treatment of the Green Party which would be to its detriment and would "suggest to the public that the Green Party is not a significant player by its exclusion".

Ms Justice Marie Baker is expected to deliver her judgment on Monday.