Whistleblower Maurice McCabe is suing Garda Commissioner Nóirín O'Sullivan and her predecessor Martin Callinan for damages arising out of his alleged treatment by them.
The case was filed just two weeks after a separate damages claim was made against Tusla and the HSE, arising out of the creation of a file containing false sexual abuse allegations against him.
Proceedings were initiated against the two commissioners on Monday.
The Justice Minister, Attorney General and the State have also been named as defendants in the case.
A statement of claim has yet to be lodged, but a source close to Sgt McCabe confirmed the case was one for damages.
It is understood a number of injunctive reliefs will also be sought.
However, it is highly unlikely the case will get under way ahead of the completion of the first module of the Disclosures Tribunal, which has been given nine months to report.
It is understood there is a significant overlap between the matters being investigated by the tribunal and the issues at the centre of the civil suit.
Mr Justice Peter Charleton is investigating allegations made in a protected disclosure by former Garda press officer David Taylor that he was instructed by Mr Callinan and/or Commissioner O'Sullivan to contact journalists and brief them negatively about Sgt McCabe.
This is alleged to have occurred after Sgt McCabe raised serious concerns about abuses of the penalty points system and the manner in which a number of cases were investigated in the Cavan/Monaghan division.
Supt Taylor has claimed he was told to brief that Sgt McCabe's complaints had no substance and that he was driven by an agenda.
He also claimed he was directed to draw journalists' attention to a false allegation of criminal misconduct made against Sgt McCabe.
The tribunal is investigating claims by Sgt McCabe that false allegations of sexual abuse were inappropriately relied upon by Ms O'Sullivan to discredit him at the commission of investigation conducted by Mr Justice Kevin O'Higgins.
Neither Ms O'Sullivan's office nor that of Justice Minister Frances Fitzgerald wished to comment last night. Mr Callinan could not be contacted.
He resigned in March 2014 following months of controversy surrounding his handling of a number of issues within the force.
He had been under pressure to withdraw remarks made at the Dáil Public Accounts Committee in which he described the actions of Sgt McCabe and another whistleblower as "disgusting".
Sgt McCabe is being represented in the case by Sean Costello & Company Solicitors.
The same law firm is also representing Sgt McCabe, his wife Lorraine and their four children in their High Court action against the HSE and Tusla.
The proceedings allege malicious falsehood, breach of privacy and breach of constitutional rights.
Damages are being sought and reliefs are also being requested compelling the HSE and Tusla to provide information and documents.
A counsellor working for the HSE contacted gardaí and Tusla in August 2013 after being made aware of an abuse allegation against Sgt McCabe.
The following May the counsellor informed Tusla that the accusation was the result of a clerical error. Tusla informed gardaí of the mistake.
However, the untrue sexual abuse claim remained on a Tusla file until at least January 2016 when a member of its staff, unaware there was no substance to it, contacted Sgt McCabe. Both Tusla and the HSE have issued apologies to the McCabes, but the apologies have been rejected.
Meanwhile, the Disclosures Tribunal will sit again in George's Hall at Dublin Castle on March 30. The tribunal will hear applications for legal representation in respect of forthcoming hearings.
The hearing will be in public, but unlike the previous sitting of the tribunal, where an opening statement was read, no permission has been given for the media to film, photograph or record the proceedings.