Published Wednesday, 07 December 2011
Prime Minister David Cameron has already accepted that there was security force collusion in the 1989 UDA gun attack, in which Mr Finucane was shot 14 times in front of his wife and children.
He invited the family to Downing Street in October, where he apologised on behalf of the Government - but Mr Finucane's widow stormed out when told there would be no public inquiry.
On Wednesday, Geraldine Finucane said: "We take the view that the decision not to hold a public judicial inquiry is just another obstacle which we will have to overcome."
Mr Cameron decided that Sir Desmond de Silva QC would review the papers on the case instead.
We are determined to get to the truth surrounding my husband's murder. Our campaign will continue.
Geraldine Finucane
But Ms Finucane has now confirmed her intention to launch a challenge in the High Court in Belfast - the legal papers will be lodged within days and a date for hearing will be sought.
"Not for the first time have we had to resort to legal proceedings to vindicate our legal rights," Ms Finucane said.
"It is clear that the British Government has cynically reneged on the commitment made at Weston Park.
"The Cameron decision is also incompatible with Article 2 of the European Convention on Human Rights (the right to life)."
During talks on the peace process at Weston Park in Shropshire in 2001, the British and Irish Governments entered into an agreement to hold inquiries into allegations that their respective security forces were linked to a number of notorious murder cases - including Pat Finucane's killing.
It was eventually agreed that the Westminster Government would conduct inquiries into four cases, while the Dublin Government would hold one inquiry.
All have been held, except the proposed probe into the Finucane case.
While collusion has been accepted, the family still wants to know who sanctioned the killing and how many of those involved were agents of the state, and to expose the full extent of the plot.