Update 1.55pm: Anyone with information relevant to the alleged smear campaign against Sergeant Maurice McCabe has been asked to come forward to the Disclosures Tribunal in the next two weeks.
Mr Justice Peter Charleton has called on people who may have information or may be a witness to the tribunal to come forward and submit a written statement to the inquiry.
Mr Justice Charleton said he wants to conclude the inquiry as quickly as possible and get to the truth.
He has warned that anyone lying is wasting taxpayers' money.
Opening the tribunal with a public statement, Mr Justice Charleton said he has one task, to establish the truth.
Update 11.05am: A judge has issued a hard-hitting warning to anyone who misleads a public inquiry into allegations Garda chiefs orchestrated a smear campaign against a high-profile whistleblower.
Supreme Court judge Peter Charleton, who heads the Disclosures Tribunal, said the investigation is being bankrolled by ordinary men and women through their taxes.
Any attempts to thwart its mission to establish the truth would be an unwelcome wasting of the money of hard-working people across the country, he said.
"This tribunal is a drain on the resources of the Irish people and it is paid for by their submission to the democratic structures of which taxation has been a central part in our tradition," the judge said.
"Every lie told to this tribunal will be a waste of what ordinary men and women have paid for through their unremitting efforts.
"Every action of obfuscation, of diversion of focus and non-cooperation is unwelcome for that reason."
Judge Charleton made his remarks in the opening address of the Disclosures Tribunal at Dublin Castle.
The tribunal will investigate an alleged smear campaign against Sergeant Maurice McCabe, including the role of the State child and family agency Tusla, relating to its file containing false allegations of sexual abuse.
It will also look at allegations of "inappropriate contacts" between the force and Tusla in relation to garda Keith Harrison and other whistleblower officers and investigate the role of the media in the scandal.
Superintendent Dave Taylor, former head of the Garda press office, made the allegation of a smear campaign against Mr McCabe in a protected disclosure last year.
"There are no preconceived notions in this tribunal as to who is a villain and who is a victim, if there are such, and it may be that what the tribunal finds will not be to everyone's taste," Judge Charleton said.
"The truth is bitter though it is not shameful."
Judge Charleton appealed for witnesses with any knowledge relating to the investigation to contact the tribunal urgently.
An interim report is expected within three months.
Judge Charleton previously worked as senior counsel to the Morris Tribunal, which spent years examining corruption and negligence among some gardai in Donegal in the 1990s.
The judge in charge of a new tribunal into Garda smearing, has questioned whether the media was used for "naked deceit".
Justice Peter Charleton is this morning giving his opening statement at the Tribunal into certain Garda disclosures.
It has been set up to examine the treatment of certain Garda whistleblowers, including Sergeant Maurice McCabe.
It is claimed that Garda Commissioner Noirín O'Sullivan told her lawyers to question Maurice McCabe's motives at a previous Commission of Investigation.
Justice Charleton says it is not clear exactly whether O'Sullivan can be forced to give evidence about her instructions.
"Is there a privilege against disclosing instructions given by a client to their lawyer, as to what is to be pursued in cross-examination," he said.
"Submissions will be heard on that matter since it is now a matter of conjecture as to what happened.
"The original transcript of the O'Higgins Commission is already in the possession of the tribunal and is being read in full."