A Catholic bishop has warned that the same arguments which are now being used to justify abortion will be used to justify ending the lives of frail older people and individuals with significant disability.
Bishop Kevin Doran has also said that simply removing the Eighth Amendment to the constitution - as recommended recently by a special Oireachtas Committee - would leave governments entirely free to introduce whatever abortion regime they choose at any time in the future.
Sligo-based Bishop Doran, who chairs the national Catholic bishops' bioethics committee, makes his comments in a pastoral letter to his diocese of Elphin two days ahead of a special cabinet meeting on the terms of the promised referendum on the repeal of the Eighth Amendment's near-blanket ban on abortion.
"This is the final frontier," the bishop declares. "If we cross it, there will be no easy way back."
He adds that if the electorate were to simply remove the Eighth Amendment - as advocated recently by an Oireachtas Committee - governments would be left entirely free to introduce whatever abortion scheme they choose at any time in the future.
He warns that promises made before the referendum would not be binding and accuses the committee of asking citizens to give the government a blank cheque.
The bishop urges members of his diocese to politely lobby their politicians to defend the right to life of the unborn.
And he advises any member his diocese who may be uncertain about how to vote - or what to do - to pray daily for the gift of wisdom, and to allow what he calls "God's Spirit" to be their guide.
The diocese of Elphin covers parts of Counties Sligo, Roscommon, Westmeath and Galway.