The final phase of the Disclosures Tribunal could run into next year.
The first public hearing in this phase is due to take place at the end of June.
In his opening statement today, Mr Justice Seán Ryan set out the terms of reference at Dublin Castle.
This phase will deal with complaints made by a member of An Garda Síochána alleging that they were targeted or discredited with the knowledge of senior members of the force, after making a protected disclosure alleging wrongdoing.
The tribunal will consider complaints made before 16 February 2017.
Diarmaid McGuinness, Senior Counsel for the tribunal, said that the first case to be heard is that of Garda Nicholas Keogh.
Judge Ryan said he anticipated this first complaint will be heard in late June, and that other cases will follow later into the year and into 2020.
He said the tribunal would deal with the admissibility of complaints made as it proceeds and that it will proceed as expeditiously as possible.
Mr Justice Ryan said that an important limitation on any consideration by the tribunal is that the focus is not on the wrongdoing reported in the Protected Disclosure, but rather on the conduct towards the Garda subsequent to the disclosure who had made the disclosure.
He said another essential requirement under the terms of reference is that the targeting or discrediting directed towards the whistleblower after the disclosure was condoned or tolerated or known about by senior members of An Garda Síochána.
The first module of the tribunal concerned Sergeant Maurice McCabe, Garda Keith Harrison and Tusla.
The final report into the McCabe matters was completed by Mr Justice Peter Charleton last November.
Mr Justice Ryan said today that the tribunal gets its jurisdiction from the terms of reference and only from them.
He said it had no independent capacity to investigate or consider complaints unless they come under the terms of reference.
The tribunal is considering complaints from both serving and retired members of An Garda Síochána.