A Dublin engineer who won his Supreme Court case that the government used €1.1m of public money to put out one-sided information on the children's referendum says he feels vindicated.
Mark McCrystal claimed the campaign was designed to promote a 'Yes' vote.
The Supreme Court has criticised some of the government's content on its referendum website and in a booklet distributed to households.
It has found public money was used in a manner which was not fair, equal or impartial and that this is in breach of the landmark McKenna judgment from 1995.
McCrystal said: "The McKenna judgment was very clear to protect the rights of Irish people and also put a limit on the way the government behaves.
"There has been a great slip in that area in the wrong direction, hopefully the government have paid proper attention to this judgment today."
Meanwhile, the Tánaiste says the government fully respects and will comply with the Supreme Court judgement.
Eamon Gilmore added that it does nothing to stop the referendum, which goes ahead as planned on Saturday: "Today's judgment does not change the fact that there is a referendum on Saturday and it does not change the arguments in favour of the referendum.
"We need to put into our constitution the rights of children explicitly expressed and have constitutional protection for adaption and the voice of children."