Mr Desmond O'Malley personally directed that a file containing the suppressed statement of Col Michael Hefferon be withheld from the second Arms Trial in 1970 just a day after the trial began.
Mr O'Malley, then minister for justice, "examined and considered" the file before directing that privilege be claimed for it and its contents on October 7th, 1970, according to a document signed by him under his official ministerial seal.
The second trial of Mr Charles Haughey and three others, began on October 6th, 1970. The five were acquitted of a conspiracy to illegally import arms.
The Department of Justice has made the signed and sealed certificate of privilege available through the National Archives under the 30-year rule.
Mr O'Malley's declaration that he had "examined and considered" the file contrasts with his statement on Wednesday that he had no recollection of seeing Col Hefferon's original statement. He said this was "not particularly surprising given the passage of 31 years".
The file in question contains statements from public servants and others, including Col Hefferon, in relation to the alleged attempt to import arms illegally.
The effect of claiming privilege was to ensure that the contents of the file, including Col Hefferon's original statement implicating the minister for defence, Mr Jim Gibbons, in the affair, was not disclosed in evidence.
The suggestion that Mr Gibbons knew of the affair was significant in that it could have cast doubt on the prosecution case that the attempted arms importation was illegal.
The copy of Col Hefferon's statement on the file has handwritten marks beside each reference to Mr Gibbons having knowledge of the plan to import arms. These marks are believed to have been made by the secretary of the Department of Justice, the late Mr Peter Berry.
The marked parts were all omitted from the statement of Col Hefferon that was included in the Book of Evidence for the first trial, which began on September 22nd, 1970.
However, after Col Hefferon gave evidence in the first aborted trial implicating Mr Gibbons along the lines of his original statement, the prosecution decided not to call him in the second trial.
That trial began on October 6th, and Mr O'Malley signed the certificate of privilege withholding the file the following day. The presiding judge ultimately called Col Hefferon after a request from the defence.
In the 1970 certificate claiming privilege Mr O'Malley said he had "examined and considered" the file, bearing the identification number S/7/70, marked "confidential" and entitled "Alleged Plans to Import Arms Illegally". This is the file containing Col Hefferon's original statement.
He said he had "formed the view and am of opinion that on grounds of public policy and interest" neither the file nor any document in it should be produced or disclosed in evidence. "I accordingly direct that privilege be claimed (a) for the said file, and (b) for the contents of each document contained therein".
He stated that the claim of privilege did not apply to the production of the file to the trial judge for private inspection. This is in accordance with a written legal opinion on file - apparently obtained in relation to an unrelated trial - that documents over which privilege is claimed should be available for inspection by the trial judge.
The Irish Times inspected the file numbered S/7/70 at the National Archives office in Dublin yesterday. The director of the archives, Dr David Craig, said yesterday he was "absolutely satisfied" all documents on the file were genuine and filed correctly.
Efforts to contact Mr O'Malley last night were unsuccessful.