Digital Rights Ireland (DRI) has begun a High Court action against the Government in a bid to challenge the new data retention laws.
The action names the Minister for Communications, Marine and Natural Resources; the Minister for Justice, Equality and Law Reform; the Garda Commissioner, Ireland and the Attorney General.
The lobby group described the new regulations, which require certain information on phone calls, e-mail and Internet usage to be kept for three years, as "mass surveillance".
The data retention laws in question, contained in the Criminal Justice (Terrorist Offences) Act 2005 and the European Data Retention Directive passed in 2006, are part of an EU-wide effort to fight organised crime and terrorist activity.
"These laws require telephone companies and Internet service providers to spy on all customers, logging their movements, their telephone calls, their e-mails, and their Internet access, and to store that information for up to three years. This information can then be accessed without any court order or other adequate safeguard," said DRI chairman TJ McIntyre.
"We believe that this is a breach of fundamental rights. We have written to the Government raising our concerns but, as they have failed to take any action, we are now forced to start legal proceedings."
According to DRI, the new laws contravene the Irish Constitution and also breach Irish and European data protection laws.
"These mass surveillance laws are a direct, deliberate attack on our right to have a private life, without undue interference by the Government. That right is underpinned in the laws of European countries and is also explicitly stated in Article 8 of the European Convention on Human Rights," said Mr McIntyre.
"We accept, of course, that law-enforcement agencies should have access to some call data. But access must be proportionate," he said.
The group's action is being supported by a number of rights groups, including Electronic Frontier Foundation, Privacy International, the European Foundation for a Free Information Infrastructure and Electronic Frontier Finland.