The broad outline of the relationship between the Revenue and Mr Charles Haughey already seems apparent, although the tribunal's inquiry into the matter has some days to run.
On one side you have Mr Haughey, one of the most powerful figures of his generation. On the other a government agency with inadequate powers to carry out its duties.
Central to the whiff of sulphur which has always surrounded Mr Haughey was the fact of his unexplained wealth. We now know that access to his files in the Revenue Commissioners would have done nothing to solve the mystery.
Everyone knew about Mr Haughey's progress from a semidetached house in Raheny in the 1950s to a Gandon mansion in Kinsealy in 1969.
We now know that at no stage did the Revenue hold an inquiry into where the money for this came from.
This remained the case after the Revenue became aware in 1984 of a transaction in 1980 involving £300,000 and a purported land deal between Mr Haughey and the Gallagher Group.
The £300,000 was not declared to the Revenue by Mr Haughey, and the Revenue became aware of it only after the collapse of the Gallagher Group.
Mr Christopher Clayton, now chief inspector of taxes with the Revenue, said if an inquiry had been opened into this transaction it would have "run into a brick wall very quickly".
The powers available to the Revenue were very limited at the time, he emphasised. Looking back on them from today's perspective, the paucity of powers then available was "shocking", he said.
Responding to Mr James Connolly SC, for the Revenue, he said to get permission from the High Court to look at a bank account the Revenue needed to show "reasonable and probable cause of non-compliance". There was no evidence of that at all in relation to the Gallagher deal, he said.
Mr Clayton's boss never gave any consideration to an inquiry. Mr Seamus Pairceir, the Revenue chairman from December 1983 to September 1987, was informed of the Gallagher deal in 1984.
His evidence yesterday was that he kept in contact with the case in order to provide "cover" for Mr Clayton in case any complaint was made.
This seems reasonable. There were three contacts in 1984, one in 1985 and four in 1986.
He himself entertained some doubt as to the validity of the contract at the heart of the Gallagher deal, suspecting that there was a possibility that it was a cover for what was in reality a donation.
There was some sensitivity about the case, given who the taxpayer was. The Revenue, as he said, did not exist in a vacuum. Also, the position was that Mr Haughey, though he had received the money in 1980, had not declared it to the Revenue, even after 1984, when the Revenue indicated to Mr Haughey that it knew of the payment.
Interestingly, when asked about this, Mr Pairceir said the situation in relation to tax compliance was so bad in the mid1980s that he would have "presumed" this non-declaration.
Seemingly, no particular high standard was expected of the leader of Fianna Fail.
Despite non-disclosure, subsequent lack of co-operation from Mr Haughey and suspicions surrounding the Gallagher deal, Mr Pairceir did not feel the case warranted further investigation.
Asked by Mr John Coughlan SC, for the tribunal, what the criteria were for opening an inquiry by the investigation branch, Mr Pairceir replied: "Non-disclosure of an asset or income."
Nevertheless, he said, "I did not give any consideration to referring the Haughey family to the investigation branch. I never thought of it and even now I don't see why I should have."