A woman whose partner was shot dead by gardaí during an attempted armed robbery of a cash-in-transit van wants the High Court to overturn a Commission of Investigation finding that he was lawfully killed.

Grainne Nic Gibb's 28-year-old partner, Ronan MacLochlainn, was shot dead in the incident in Ashford, Co Wicklow, in 1998.

Lawyers for Ms Nic Gibb claimed gardaí could have stopped the attempted robbery beforehand and arrested Mr McLochlainn but instead "went for the spectacular".

Ms Nic Gibb wants the court to delete the commission's finding from its draft report and make findings about the adequacy of the evidence on which the disputed finding was made.

The commission, whose sole member is senior counsel Mary Rose Gearty, was set up in 2014 and heard 60 days of evidence.

Ms Justice Mary Faherty adjourned the case to later this month to consider the report and submissions.

Neither Ms Gearty nor the Garda Commissioner, a notice party to the case, were represented.

The commission was set up after Ms Nic Gibb brought proceedings in the European Court of Justice following an inquest in 2010.  

Ms NicGibb's solicitor, James MacGuill, said it was his client's case the commission's finding of lawful killing was unsafe.  

There were "unexplained gaps" in evidence and a combination of factors that made it impossible for an independent fact finder to safely come to a conclusion.

Mr MacGuill said a dissident IRA group was put under surveillance in 1998 by the Garda National Surveillance Unit.  

Tracking devices were attached to two vans parked in Heuston Station car park in Dublin in April 1998.

One of the gaps in evidence related to CCTV footage from Heuston in which Mr MacLochlainn was observed transferring a sports-type bag from one van and putting it in a car.  There was no explanation why that footage was no longer available.

When they arrived in Ashford on 1 May, the occupants of the vans, dressed in overalls, got out and put up signs to stop traffic.  

The commission heard gardaí believed there was going to be a kidnapping or high value robbery, or explosives were to be transferred, and an officer realised the target was a cash-in-transit van on its way to the scene.

An issue arose whether action should have been taken at this stage to stop it, perhaps by simply parking a police car on the opposite side of the road, Mr MacGuill said.

However, gardai arrived and an attack was mounted on the vans with members of the NSU and Garda Emergency Response Unit involved.

While an initial garda statement said shots were exchanged, only gardaí discharged their weapons and there was an issue whether gardaí were entitled to open fire on the basis of a legitimate apprehension their lives were in danger, Mr MacGuill said.

Mr MacLochlainn, who was armed, sought to flee and hi-jacked another vehicle. From that point on, it was very difficult to reconcile the available evidence, the solicitor said.  

This included matters related to damage from a collision between the vehicle Mr MacLochlain was in and garda vehicles, the location afterwards of a firearm in the vehicle or on the road, and preservation of garda vehicles at the scene. There were 42 members of the ERU and the NSU involved that day.

While a detective superintendent issued a direction no vehicles were to be moved, a lower-ranking ERU officer effectively countermanded that order, removing an opportunity for proper reconstruction of what happened, Mr MacGuill said.

There was no principal commander in place and failure to have a handover point when it became a crime scene, he said.  

A vital daybook type ledger used by gardaí to record matters, to which documents were attached, was no longer available, he added.