The Taoiseach had "rolled over" in the face of pressure from EU partners after the last Nice referendum, the former Labour attorney general, Mr John Rogers SC, has claimed.
"The Irish people decided against Nice and that has been ignored," he added. Objecting to Mr Ahern's description of anti-Nice campaigners as "dingbats", Mr Rogers told RTE Radio's This Week programme: "I find it very surprising that the Taoiseach would use that type of language on this very serious issue in respect of which the people have already stated their position."
He continued: "Regrettably, it does seem that the Taoiseach, Mr Ahern and [Minister for Foreign Affairs] Mr Cowen have not taken seriously what happened last year when the people made the decision about this. In fact, immediately after the decision it would appear that Mr Cowen and Mr Ahern resolved that, despite the democratic decision of this country, we would be told that we had to go into full approval of the Nice Treaty.
"Instead of going out to the [EU summit] meeting in Gothenburg and advising the leaders of the Union that the Irish people had significant substantial reservations about Nice to the extent that they rejected it, the Taoiseach in a sense went out and rolled over and acquiesced in the decision of the Irish people being ignored and the Irish people being, in effect, now told by their domestic leaders that they must approve Nice."
He continued: "We are full members of the Union. We have done nothing to cause us to be expelled from the Union. We are entitled to participate in all the institutions of the Union. And will continue to do so if we reject Nice a second time. I am amazed by the people I see expressing doomsday situations. Really telling us that, you know, the game will be up for Ireland. That is entirely unsustainable."
He said it was "important to democracy in the Union that small states like Ireland are not pushed around". Criticising EU leaders, he said they "took Ireland for granted" after the last referendum.
"If the Union is not going to respect democratic principle we must signal - we, the Irish people, must signify - that it cannot have our respect. It is as simple as that," Mr Rogers said.
The Sinn Féin TD, Mr Aengus Ó Snodaigh said there was "a lot of anger out there" at the decision to present the treaty for a second vote. Starting this week, "hundreds of party members" would be canvassing in Dublin.
Meanwhile, a telephone poll published in Ireland on Sunday yesterday shows 37 per cent in favour of Nice, 19 per cent against, 35 per cent undecided and 9 per cent not voting.
But only 44 per cent said they had a "good understanding" of the issues. A total of 1,001 people were surveyed by ICM research last Wednesday and Thursday.