Relatives of Bloody Sunday victims are to appeal against a Belfast High Court ruling this week enabling police witnesses to give evidence to the inquiry into the event from behind protective screens.
Madden and Finucane law firm have lodged papers with the Court of Appeal to challenge the decision by a judicial review earlier this week to uphold a Saville Inquiry ruling allowing 20 police witnesses to be shielded from public view when they take the witness stand.
The families of Bloody Sunday victims are challenging the ruling because they believe it could be followed by applications by soldiers to also give evidence from behind screens.
On Tuesday, Mr Justice Kerr backed the decision by the Bloody Sunday inquiry that 20 serving and retired officers should have their identity concealed because of fears that their identification would make them more vulnerable to Republican terrorist attack.
Dismissing an application by Mrs Mary Doherty, the sister of Gerard Donaghy, who was killed on Bloody Sunday, the judge said security risk assessments supplied to the inquiry by the police provided "ample material" for the witnesses to apply for protected screening.
In a 35-page ruling, Mr Justice Kerr said: "Any police officer who was informed that the provisional IRA was continuing to gather intelligence about policemen's movements and that there was contact between PIRA and dissident Republican groups is bound to be concerned.