THE Government has vowed to operate within court guidance when publicising referendums after promotional material for the children's rights vote was deemed not fair, equal, impartial or neutral.
Mark McCrystal, the engineer whose legal challenge exposed the error, called for resignations over the misuse of some of the €1.9m publicity campaign.
"The Government has gone well beyond its powers in doing serious damage to democracy and freedom in this country. This has to be addressed seriously," he said.
"I think heads should roll big time on this. I think it's an intolerable situation for this to happen."
Mr McCrystal contested that the Government was in breach of rules set down by the 1995 McKenna judgment which bars public funds being used to promote a vote one way or another in a referendum.
Material was carried in a booklet delivered to every home, a website and adverts.
Among the issues raised in the case was the wording of phrases such as "Protecting Children", "Supporting Families", images depicting a smiley face and an inference in the material that a referendum was needed.
In a statement, the Government said it was carefully studying the Supreme Court judgment, delivered in full today after an initial ruling over a month ago.
It said it welcomed guidelines from the court and would in future act within the limitations.
"The court unanimously acknowledged that the principle enunciated in the McKenna judgment stands as firm as ever, but the modes through which information is conveyed are very different to those which were operating in 1995," it said.
"The court has found that the Government, in attempting to fulfil this duty to inform the people, strayed beyond the boundary of the provision of information to the electorate.
"The court found that the Government at all times acted in a bona fide manner and all the publications were issued with a view to informing the electorate about the referendum."
In the Supreme Court ruling, Chief Justice Susan Denham highlighted the use of a link to "like" on the Government website childrensreferendum.ie.
She said it was associated with Facebook and that it was removed because there was no option but to click the link.
"This illustrated the campaigning tone of the website in favour of a yes vote and indeed it was removed by the respondents when objections were made by the appellant," she said.
Judge John L Murray found: "Taking the material as a whole, one is driven to the ineluctable conclusion that it advocated the case for a yes vote without explicitly calling for a yes vote.
"This was done, with the aid of public funds, to the disadvantage and detriment of those making the case for a no vote."
Also on the five-judge court, Judge Donal O'Donnell added: "The most valued position in politics, is the appearance of being above politics.
"The fact that the message here cannot necessarily be described as strident, blatant and egregious, or campaigning advocacy or propaganda, is to miss the point."