Fine Gael has called for the proposed Privacy Bill to be scrapped, claiming it would "cripple investigative journalism, gag the media and do little to protect members of the public".
Fine Gael justice spokesman Jim O'Keeffe said the Bill was "a dangerous piece of legislation".
"The right to privacy already exists in Irish law and has been recognised repeatedly in the courts. But this new Privacy Bill will add little to existing rights while restricting the power of the press to investigate wrong-doing.
"This Government is not really worried about protecting members of the public from intrusion by the media. It only cares about protecting its own members. Justice Minister Michael McDowell, who had earlier spoken out against privacy measures, was backed into a corner and forced to draft the Privacy Bill by his Fianna Fáil colleagues."
Meanwhile, an international expert on press regulation has said the planned Privacy Bill would have a "chilling effect on the conduct of responsible investigative journalism".
Prof Robert Pinker, international consultant to the British Press Complaints Commission and its acting chairman from 2002 to 2003, was speaking at a conference hosted by the law school at Trinity College at the weekend on defamation, privacy and media regulation.
It looked at the new Defamation and Privacy Bills. The Defamation Bill will set the ground rules for defamation and the principles governing the establishment of an independent press ombudsman and press council.
The Privacy Bill will put in place constraints on news gathering. Among the functions of the press council will be to oversee the implementation of the privacy legislation and to advise media professionals on its provisions.
Both Bills are due before the Houses of the Oireachtas for debate next year.
Prof Pinker said the Privacy Bill would "have serious implications for the conduct of effective press regulation".
Describing the Bill as "draconian", he said it did "not offer precise enough definitions of such crucially-important terms as 'surveillance', 'harassment', 'news gathering', 'the public interest' or 'the attributes of privacy' for a council to safely answer that vital question - is it safe legally?
"And given the Bill's wide-ranging prior restraints, the Irish council is likely to be inundated with editorial requests for clarification and guidance on these matters."
Privacy laws were based in the circumstances of their time. He said they made it "far more difficult for councils to respond swiftly and flexibly to changing circumstances and events".
"We live in a rapidly changing world. The trend towards greater convergence between print, broadcast and on-line media is gathering momentum, as is the number of on-line publications.
"Under such circumstances I suggest it makes better sense to leave the development of various laws concerned with privacy intrusion to the courts."
He also warned of the "new and highly pre-emptive forms of prior restraint" the Privacy Bill would impose on members of the public. "The rights of citizens - as complainants and litigants in privacy cases - will be enhanced but so will the degree of protection afforded to a legion of 'public servants' invested with the authority to invade every citizen's privacy," he said.