The family of murdered solicitor Pat Finucane has been granted a judicial review of the decision not to hold a public inquiry into his death.
A Belfast High Court hearing in May will last for three days.
He was killed at his north Belfast home by loyalist gunmen in 1989.
UK Prime Minister David Cameron earlier this year accepted there had been collusion in the killing.
Mr Finucane's widow Geraldine said: "I am very pleased that he has granted us leave to go forward to a full judicial review hearing and I think the significant aspect of it was that it was completely unopposed (by the Government).
"It was surprising but a very pleasant surprise for a change."
High Court judge Mr Justice Ben Stephens granted the review.
Mr Cameron announced last autumn that instead of ordering a public inquiry he was appointing lawyer Sir Desmond de Silva to consider evidence in the case. That decision has been denounced by Mr Finucane's family.
Mrs Finucane said she would not be co-operating with Mr de Silva but welcomed the three-day legal challenge planned for 9 May.
She said they were promised a public inquiry by the Government.
"For the British Government to turn around and unilaterally decide to change that and say that a review of the papers is the way forward left us no other way to do this than to push for a judicial review," she said.
She added: "It is only the start but it was unopposed and we will then move forward to a full hearing."
Taoiseach Enda Kenny has said he will wait to see the judgement in relation to calls for an enquiry by the Finucane family before commenting, saying he had discussed the matter with UK Prime Minister David Cameron.
Deputy British Prime Minister Nick Clegg said he hoped people would appreciate the "signifance" of previous apologies and acknowledments of collusion issued by the British Government.
Northern Ireland First Minister Peter Robinson said he had previously acknowledged the pain of the Finucane family, but had also pointed out to them that over 3,000 other families would not be granted judicial investigations.
They were speaking at the closing press conference of the British-Irish Council in Dublin.
Sinn Féin President Gerry Adams welcomed the decision to hold a full judicial review.
He said: "The Irish government must relentlessly press the British government on this issue through every diplomatic means and at every international institution open to it."