A brother of one of those shot dead on Bloody Sunday has launched a legal bid to prevent the formal ending of murder charges Soldier F.
Michael McKinney wants the High Court to impose an order ahead of his challenge to the decision not to prosecute the British army veteran.
Thirteen people were killed when members of the Parachute Regiment opened fire on civil rights demonstrators in Derry on January 30, 1972. Another of those wounded on the day died later.
Soldier F was charged with the murders of William McKinney and James Wray, plus five counts of attempted murder.
Last week, Northern Ireland’s Public Prosecution Service (PPS) announced that he will not stand trial after an assessment of the evidence found the test for prosecution had not been met.
Criminal proceedings against Soldier F are due to be discontinued on Friday.
Mr McKinney is set to judicially review the PPS decision and his lawyers are seeking an interim order to stop the ex-paratrooper from being discharged.
Relatives of five of the Bloody Sunday victims are taking separate legal action against previous decisions not to charge former soldiers with their murders.
That case is listed for hearing in September, and Mrs Justice Keegan pointed to parallels in the two challenges.
During the preliminary exchanges, counsel for Soldier F indicated opposition to any order being made to prevent the prosecution being discontinued.
Mark Mulholland QC argued that his client would be left in a state of uncertainty.
“This accused enjoys the presumption of innocence,” he stressed.
Mr Mullholland added: "Discontinuance is not an acquittal, the law does permit the re-instigation of criminal proceedings at the committal stage."
Judges are expected to rule on the application for interim relief on Thursday.
Outside court Mr McKinney’s solicitor pointed out that if his challenge ultimately succeeds the prosecution of Soldier F will probably be revived.
Fearghal Shiels, of Madden & Finucane law firm, said: "There would be no prejudice caused to Soldier F by keeping the proceedings live before the court.
"He is not in custody or subject to any bail conditions, and in fact is still at risk of prosecution for the murder of Michael Kelly in separate proceedings already before the High Court."