Affected residents in Monaghan, Cavan and Meath say they will continue to oppose the North-South Interconnector, despite the Supreme Court upholding planning approval for the southern section of the project.
Planning for the project was initially granted by An Bord Pleanala in December 2016. Since then it has been the subject to judicial review proceedings.
These were dismissed by the High Court in August 2017 but the judgement was appealed, which culminated in the case being brought to the Supreme Court.
Liam Ryan, director of grid development and interconnection at EirGrid, said it was pleased the project had cleared “all of the planning and legal hurdles in Ireland”.
He added EirGrid is hopeful the same could be achieved in Northern Ireland in the coming months.
Residents who are opposed to the interconnector say the Supreme Court rulings change nothing.
In a statement the North East Pylon Pressure (NEPP) group said: “The ruling today is very much related to the An Bord Pleanála approval in 2016. It does not address or have any impact on the ongoing issues facing Eirgrid and ESB.
“The two key issues in relation to the challenges ahead – those related to access to landowners’ properties and the impact of Brexit on the future status of the project – were not considered by the court.”
NEPP contends that the original planning application did not request permission for access routes.
“No agreement for access exists at landowner level. Any attempts by ESB and EirGrid to request the local authorities to vary any of the conditions imposed will be challenged by landowners, one by one, at the appropriate time.
“Now is the time to stand firm. Eirgrid and ESB will try to divide and conquer by making a big deal out of today’s ruling,” NEPP said.