Boxing coach Pete Taylor and his partner Karen Brown have issued personal injury proceedings over the shooting incident at his club two years ago.
Mr Taylor (58), who is the father and former coach of world lightweight champion Katie Taylor, was shot in the arm during the attack at Bray Boxing Club in June 2018.
The shocking incident claimed the life of his close friend Bobby Messett (50), while another gym patron, Ian Britton (37), was shot in the leg but survived.
Following the incident Mr Taylor became embroiled in an as yet unresolved legal dispute with Wicklow County Council, which owns the gym, over access to the premises.
Now the famous coach has initiated another set of High Court proceedings, this time seeking damages for physical and psychological injuries suffered as a result of the gun attack.
Ms Brown (32), who was not present at the time of the shooting but arrived at the scene afterwards, has also lodged a separate personal injuries action in which she claims to have suffered from nervous shock.
Both cases were initiated on Tuesday. The couple are being represented by Dublin solicitors firm Robinson O'Neill.
The actions are against the Irish Athletic Boxing Association (IABA), Mr Taylor and Ms Brown's own company, Bray Boxing Club Ltd, and Wicklow County Council.
It is understood the insurance policy for the gym was taken out via membership of the IABA, while the council faces a claim under the Occupiers' Liability Act.
The cases first went to the Personal Injuries Assessment Board (PIAB), but it issued an authorisation for the claims to be taken through the court system instead.
The PIAB is not required to make assessments in cases involving a claim of psychological damage.
Mr Taylor has also made an application to the Criminal Injuries Compensation Tribunal, but this can be dealt with only if he has exhausted other potential remedies.
There is no suggestion Mr Taylor or the other men shot had any involvement in crime.
A man is awaiting trial over Mr Messett's murder.
Mr Taylor said he was shot after he ran at the gunman, who opened fire during an early morning fitness session at the Harbour Road gym.
There were around 15 people there at the time.
The bullet that hit Mr Taylor shattered his humerus before exiting through his chest, passing very close to his heart.
He had been training boxers at the club since 1995 and helped guide his own daughter to Olympic gold in 2012.
Katie Taylor won 18 major gold medals while she was a member of the club.
It had over 100 members at the time of the shooting.
But Mr Taylor has been unable to return to the gym since then after the council took possession of the premises.
In a separate legal action initiated last August, Mr Taylor and Bray Boxing Club Ltd sued the council after his efforts to regain the use of the premises were unsuccessful.
In a legal filing, the plaintiffs said they were seeking an injunction compelling the council to allow Mr Taylor to re-enter the premises on foot of a number of licence agreements dating back to 2007.
The most recent of these was entered into in 2014.
As part of the case, Mr Taylor is seeking injunctions restraining the council from selling or leasing the building or items he owns that remain at the premises.
These include gym equipment and valuable items of sentimental value.
The filing also alleged items belonging to other club members remained at the facility.
The coach is also seeking damages, claiming the council had intentionally interfered with his economic interests.
The case remains at a preliminary stage and the council has yet to file a defence.
It has declined to comment on either of the legal actions being taken by Mr Taylor.