Environmental activists who lost a High Court challenge to the State's climate action policy are now considering an appeal.
Friends of the Irish Environment (FOIE) said it was encouraged that its right to take the case was upheld and would take time to examine Mr Justice Michael McGrath's judgment. It said it was pleased he had accepted the seriousness of the issues it raised and its right to do so.
Clodagh Daly, environmental researcher, said the overall outcome of the case was disappointing, but added: "We've lost a case, not hope.
"All throughout the case, the Government argued that we did not have a right to take it but that right has been fully upheld and that's extremely important for us because there will be other cases. We intend to continue holding governments to account," she said.
FOIE, backed by a coalition of environmental groups and 16,000 public signatories, took Ireland's first climate litigation case against the Government's National Mitigation Plan, the 2017 strategy which was meant to show how the country would reduce greenhouse gas emissions up to 2050.
The plan was roundly criticised as weak in its ambitions and vague on practical actions by both environmental groups and the Government's own Climate Action Advisory Council.
FOIE argued that because of its weaknesses, it did not meet the legal requirements of the landmark Climate and Low Carbon Development Act 2015, and breached the Constitution and international human rights obligations.
The NGO asked the court to quash the plan and order the Government to produce an alternative that would properly tackle carbon emissions and protect against the risks of floods, drought, fires, ecological destruction and loss of life that climate change poses.
The Government accepted the flaws in the plan and replaced it with the Climate Action Plan published in June this year but defended the case on the grounds that asking the courts to adjudicate on it amounted to judicial interference in government policy.
Reading from his lengthy judgment to a full court room, Mr Justice McGrath emphasised the seriousness of the issues raised. "This has been a very complex case involving very difficult issues of law and science," he said.
The Department of Climate Action said later the Government was now focused on implementing the Climate Action Plan.
"Our plan will give Ireland a cleaner, safer and more sustainable future," a spokesperson said.
The spokesperson added: "The Government notes the outcome of this case and will carefully consider the judgment."
Mr Justice McGrath will make his full written judgment available today. Ms Daly said she was keen to study the judge's conclusions on the NGO's contention that a healthy environment was a human right.
That contention was backed by another High Court judge in a separate FOIE case, the first time the environment has been declared a human right in this way.
Reacting to the ruling, Jennifer Higgins of Christian Aid Ireland said aspects of it were valuable in affirming the responsibility of governments to climate action.
"Despite the result, this case has shown that only governments have the power to slash greenhouse gasses to the extent necessary to keep global temperatures within safe limits," she said.
Environmental law expert Brendan Slattery, of McCann FitzGerald, said: "The point of a case like this is never just winning or losing. It has already had lasting impact.
"I have no doubt that the case was chief among motives for urgent delivery by the Government of its Climate Action Plan in June."