Legislation being drawn up will make it unlikely any banking probe will be able to scrutinise actions of former ministers or taoisigh, such as Brian Cowen, and their handling of the banking crisis and guarantee.

TDs and senators with the Oireachtas Public Accounts Committee (PAC) were given the special confidential briefing of the planned legislation, seen by the Irish Examiner, a week ago.

“We were told that no findings of facts could be made against previous office holders and only could be made relating to future legislation. There’s a lot of confusion over this as it would essentially mean any banking inquiry is a sham,” said one Government TD.

The briefing was given by officials with Public Expenditure Brendan Howlin’s department, overseeing the drafting of the Oireachtas (Inquiries, Privileges and Procedures) Bill 2012.

The laws will set out how the Oireachtas can conduct future parliamentary inquiries and will pave the way for the long-awaited parliamentary inquiry into the banking crisis.

Documents handed to members with an overview of the inquiries state: “The Dáil has an implicit constitutional power to conduct inquiries in order to hold the Government responsible, even if this affects the reputations of individual [but that] does not extend to investigating the activities of past governments.”

The briefing documents state legislation will underpin five types of inquiries.

However, committees will only be able to examine past office holders in government under two types of limited inquiries.

One is a straightforward inquiry or reporting of events which can only make findings about uncontested facts. The other is where information on past events might help shape a forward-looking issue, such as new legislation. However, the document given to TDs specifically says the second type of investigation “would not be permitted to make findings which have a direct adverse effect on the reputation of an individual”.

Mr Howlin’s department pointed to restrictions set by the 2002 Abbeylara court judgement which ruled Oireachtas inquiries do not have the power to make findings or expressions of opinion against the good name of citizens.

Mr Howlin’s spokesw-oman said: “While such inquiries can look into the activities of past governments, it is important to note they cannot make findings having a direct adverse affect on the reputation of individuals.”

The other three types of inquiries relate to the removal of certain office holders such as judges; inquiries on the conduct of an Oireachtas member and findings of fact for the purpose of holding the current Government to account.

Mr Howlin wants to publish and introduce his legislation before the summer.