The Taoiseach has been called upon to launch an independent inquiry into Minister for Justice Michael McDowell's use of Garda intelligence in his attack on the executive director of the Centre for Public Inquiry (CPI), Frank Connolly.
Aisling Reidy of the Irish Council for Civil Liberties (ICCL) said allegations of a criminal nature had been made by Mr McDowell to seek closure of the CPI.
Mr Connolly has denied being involved in a plot to train Colombian rebels in the use of explosives which involved him travelling under a false passport to the south American country in 2001, as alleged by Mr McDowell.
"Abuse of ministerial power, abuse of Garda information, resources and functions, and abrogation of constitutional guarantees to the individual of protection from abuse of the State are genuine threats to democracy and the rule of law," Ms Reidy said.
Among the issues the inquiry should cover are: the leaking of Garda intelligence to a national newspaper; the invocation of state security as a reason for obtaining a Garda file and the use of the information "to further political objectives".
The Minister's actions should be assessed in light of Mr Connolly's constitutional and human rights, such as the right to due process; the right to one's good name and the right to freedom of expression.
The ICCL also want the inquiry to examine whether Mr McDowell had usurped powers reserved under the Constitution for the Garda, the DPP and the judiciary.
The allegations made by Mr McDowell raised a question over whether the Garda Siochana's imperative to be free from partisan political use was contravened.
"The inquiry must be carried out by an independent legal expert, who must be entitled to examine all information relating to the actions of the Minister, including security files, and must be entitled to question all and every relevant official and member of the Garda Síochána," Ms Reidy said.
"The recent events, from the leak of information from a Garda file to a national newspaper leading to the potential enforced closure of an independent watchdog body, raise fundamental questions about how robust our democracy is, and how confident we can be in limits and safeguards on abuse of State power.
"The handling of this is a watershed incident for the rule of law and the right to independent voices in civil society. If this goes unchecked, or worse seen as an accepted and condoned way for a Minister to act, then we all have to question what the real threat to democracy is," Ms Reidy added.