The No to Nice campaign has today been granted the right to seek an injunction against the Taoiseach which may see him appear before the High Court tomorrow morning.
No to Nice spokesman Mr Sean O'Domhnaill told Mr Justice Roderick Murphy that Mr Ahern made "scurrilous remarks" last Saturday in Killarney, Co Kerry regarding the campaign's funding.
Mr Ahern said last Saturday that the No to Nice campaign had received £100,000 funding from a right-wing American fundamentalist group. Mr Ahern's office later said in a statement that the comment was "a hunch"
Mr O'Domhnaill was seeking an injunction to restrain the Taoiseach from repeating these remarks and was also seeking damages from the High Court for what he called "malicious comments".
Mr Justice Murphy granted him a "short service order" which will allow the No to Nice campaign to serve Mr Ahern this afternoon to appear before the High Court tomorrow morning.
The "short service order" was granted because of the proximity of the Thursday referendum.
Mr O'Domhnaill said that Mr Ahern's comments were a falsehood and said the No to Nice campaign had received $125 from one individual in the United States, a £1,000 donation from the North and three £10 donations from Britain. He added that in total his group had spent £23,000 on the campaign.
He said the Taoiseach was "throwing mud" three days before the poll and "intended to undermine our campaign".
Any damages, he said, would awarded would go towards the No to Nice campaign.
Speaking after the case No to Nice spokesman Mr Justin Barrett said they were absolutely delighted with the ruling.
He said the Taoiseach's comments were an "interference with democracy".