We have been this way before. Some central pillar of the State or economy - the beef industry, the Blood Transfusion Service Board, the planning system or, as at present, the Revenue Commissioners and/or the AIB - has disgraced itself. Yet the appropriate State watchdog has failed to bark.

And always the politicians are involved because in our much-governed State politicians are involved in everything, good as well as bad (though the former is often forgotten). Downstream, legal sanctions, either in the criminal or civil realm, beckon, though somehow are never reached. Love's old sweet song indeed.

This time there are also disputed issues which it is important in the public interest to plumb. Such as how much the Revenue Commissioners knew before they reached the fateful settlement? Or whether any other financial institutions were involved?

The more difficult question is whether the Public Accounts Committee will be legally free to make the necessary full investigation and publish its results.

The first sign of difficulty appeared last week when the committee was forced to break off its investigation at a time when the public interest was at its height to modify its terms of reference.

The reason given for this interruption was the sage remark of Labour's Derek McDowell, who is a solicitor: "The moment the committee starts getting too close to the bone, the moment it hits a raw nerve, as sure as night follows day a High Court injunction will be sought to stop it in its tracks."

The particular difficulty on which Mr McDowell focused was that the present terms of reference of the PAC entitle it merely to "examine and report upon the accounts showing the appropriation of the sums granted by the Dail to meet the public expenditure".

Accordingly, a motion was passed to add to these terms so as to refer specifically to the episode involving the AIB. Was this really necessary? It might be thought not on two grounds.

The first is that the separation of powers of government doctrine requires the internal proceedings of the Oireachtas to be regulated by the Houses alone, so that no court would have jurisdiction to intervene. However, we know from the Re Jock Haughey case (which also happened to involve the PAC through its investigation into the fate of money voted for Northern Ireland Red Cross relief in 1970) that this kind of no-jurisdiction argument is a non-runner.

Secondly, despite the absence of explicit mention, it might be expected that the committee's natural practice of considering the State's failure to collect monies due to it (the practice also followed by the Comptroller and Auditor-General) might by now be regarded as an implicit matter of custom and practice and, consequently, justified on this basis. However, given the temper of the courts, the PAC's legal advice - that it was better to be safe than sorry - was probably correct.

There is a second and worse snare lying in wait for the committee's investigation. It was established, again by Re Haughey, that an Oireachtas committee has to follow the full rules of fair procedure (Constitutional Justice) which apply to tribunals of inquiry.

The case brought by Mr Charles Haughey against the Moriarty tribunal this summer tightened this even further. Put briefly, what that judgment does is to apply to a tribunal the same law requiring a hearing before a discovery of documents order is made, as would have to be observed in a court case. The Supreme Court did not advert to the fact that there are major contrasts between a tribunal and a court.

But the genie is now out of the bottle and there seems nothing to stop the AIB invoking the Haughey precedent against the PAC if the committee wishes to see its documents.

As we know, this luxuriant helping of fair procedure tows with it massive legal costs. In addition, all this heavy legalisation makes for massive delay and affords first-rate opportunities for obfuscation.

The latter is significant since the main point of any public inquiry is to enable the public to know what the rich and powerful are doing in their State without having to take a law degree to follow it.

The unpopularity of the legal costs incurred by the taxpayer in the beef tribunal meant that alternative forms of inquiry were sought. Two of these - the non-statutory (earlier) hepatitis C (preceding the Finlay tribunal) and the Dunnes Stores tribunals - failed because they lacked subpoena power.

The third example is the Dail Committee on Legislation and Security inquiry into the fall of the Fianna Fail/ Labour government.

This inquiry received legal advice that, unless it was equipped with a battery of lawyers, it was caught between a rock and a hard place.

Specifically, it had to choose between the expense and delay endemic in legal representation and, on the other hand, an unsatisfactory inquiry. It chose the latter in that it abstained from making any findings of fact, a remarkable constraint on a fact-finding inquiry.

We have yet to be told which of these hard choices the PAC will prefer in the present episode. But be sure, choose it must.

Finally, one should recall the precedent in which the High Court honoured the privacy of the individual over the community interest by barring the publication of one of the Comptroller and Auditor-General's reports.

The same thing might happen here, especially if the committee finds it necessary to delve into the conduct of specific non-resident account holders.

Amid all this doubt and despair, there is one bit of solid ground to which one can cling. As a result of the Committees of the Oireachtas (Compellability of Witnesses) Act, 1997, it is now a criminal offence for anyone to refuse to appear before a committee; to fail to answer its questions truthfully; or to refuse to produce any documents it requires.

This elementary point bears stating in view of the fact that some potential witnesses before tribunals have used words like "co-operate" (a word which, unfortunately, echoes the word "negotiate").

For example, an argument coming from Mr Ray Burke's camp seems to be that, because the (unfortunately named) Flood tribunal is said to have leaked, Mr Burke is therefore entitled not to answer its questions. However, even if this accusation is correct, it does not follow that Mr Burke would have any defence if he defied the tribunal.

In summary, the bull point here is that, in a world in which information is power, the people wish to ascertain certain facts in which they have a legitimate interest.

We have just established a model Freedom of Information Act, covering governmental information. However, when it comes to information relating to powerful or business interests, the position is very different.

The public right to know in this context is frustrated by the fact that the judges, with the best will in the world, have set such a strong emphasis on individual rights, with scant regard to the community interest.

It all unhappily recalls Baroness Thatcher's remark: "There is no such thing as society!" It is quite likely that a hobbled PAC investigation will be the next victim of this trend.

David Gwynn Morgan is professor of law at University College Cork