Fine Gael TD Regina Doherty has complained to Justice Minister Frances Fitzgerald about the treatment of a group of gardaí who were investigated by the Garda Ombudsman.
Ms Doherty also wrote to Garda Commissioner Noirin O'Sullivan on behalf of the gardaí, who, she said, were subjected to a lengthy Garda Siochana Ombudsman Commission (GSOC) investigation following an allegation of assault.
The investigation collapsed when it went to court despite years of investigation, according to Ms Doherty. However, she said the case is still open and the gardaí face being prosecuted at a later date.
Ms Doherty said the case was based on "unsubstantiated allegations of assault" by a person who was initially arrested by gardaí.
"The allegation from the case is still left hanging over those particular gardaí and that is unacceptable," Mr Doherty told the Irish Independent.
She said gardaí have "no recourse" to have their case reviewed if they have concerns with GSOC.
"There are no processes or avenues for gardaí who are unhappy with how they have been treated during a GSOC investigation or the outcomes of an investigation," she said.
She also complained that it was not fair GSOC is allowed to investigate incidents gardaí are currently investigating.
The details emerged in the same week as a separate controversy over the death of Sgt Michael Galvin in Co Donegal.
Her comments come as Taoiseach Enda Kenny said it is "right and proper" to have a judicial inquiry into the events leading up to the tragic death.
Mr Kenny sent his sympathies to Sgt Galvin's family and praised the garda, who he described as an "exceptional person recognised as a wonderful "community activist".
Sgt Galvin took his own life in Ballyshannon Garda Station in Donegal, after being subjected to a Garda Siochana Ombudsman Commission (GSOC) investigation.
Justice Minister Frances Fitzgerald met with the Association of Garda Sergeants and Inspectors (AGSI), which has been critical of GSOC's handling of the investigation into Sgt Galvin.
Ms Fitzgerald subsequently initiated a judicial inquiry.
Speaking at the North South Ministerial Council meeting in Dublin Castle, Mr Kenny said he hoped the inquiry will be deal with the matter "very clearly and very promptly".
"Clearly anything that happens here will not bring back the deceased member of the force and our sympathies again to his wife and young family," the Taoiseach said.
"The minister has asked the Supreme Court Chief Justice to appoint a suitable member from either the Supreme Court or the High Court to carry out an independent investigation into what happened here. That's right and proper, and this is the first time this has been used."
Tánaiste Joan Burton also said she was "absolutely saddened" by Sgt Galvin's death and offered her condolences to his family. The Tánaiste welcomed the judicial inquiry established by Ms Fitzgerald.
"This is a terribly distressing event for Sgt Galvin's family, but also for the whole community that he worked and lived in.
"But I'm happy to say that the Justice Minister has moved to opening a judge-led independent inquiry and I understand that the Galvin family would welcome such an investigation.
"I certainly hope that the investigation can give them the answers they need," he added.