The plan has been knocked down because it lacks specificity and does not comply with Ireland’s obligations under the Climate Action and Low Carbon Development Act 2015.
That Act requires sufficient detail to be given about achieving a national transition to a low carbon economy by the end of 2050.
The government will now have to devise a new plan.
Friends of the Irish Environment (FIE) had claimed the National Mitigation Plan 2017-22 (NMP) lacks urgent measures to substantially reduce emissions and thus breaches rights to life, bodily integrity and a healthy environment under the Constitution and European Convention of Human Rights (ECHR).
The NMP is also inconsistent with the State’s obligations under Section 4 of the Climate Action and Low Carbon Development Act 2015 to achieve Ireland’s transition to a low carbon, climate resilient and environmentally sustainable economy by end 2050, FIE argues.
The State argued the FIE case is an “attack on policy choices” made by government and an impermissible attempt to have the court prescribe government policy on emissions.
In a judgment delivered via video link on Friday, Chief Justice Frank Clarke, with whom Judges Mary Irvine, Donal O’Donnell, John MacMenamin, Elizabeth Dunne, Iseult O’Malley and Marie Baker agreed, allowed the appeal.
The case was brought against the Government, Ireland and the Attorney General.
FIE argued the NMP fails to set out measures to substantially reduce emissions by 20 per cent by 2020 and further reductions in the short to medium term.
It says such measures are required under the 2015 Act and EU and international agreements and the failure to provide for them breaches the rights to life, bodily integrity and a healthy environment.
FIE secured the “leapfrog” appeal directly to the Supreme Court after the High Court rejected its case. The issues raised include the availability of judicial challenge to the legality of the plan and the broader environmental rights asserted under the Constitution, ECHR and/or from Ireland's international obligations.