THE taxpayer could end up paying as much as €500,000 to contest former senator Ivor Callely's appeal against his Seanad suspension.
In July 2010, a Seanad committee found Mr Callely had misrepresented his normal place of residence when claiming allowances and suspended him from the house.
But the High Court found that his right to fair procedures and natural justice had been breached and he was entitled to compensation of €17,000.
Kieran Coughlan, the clerk of the Dail, yesterday told the Dail's Public Accounts Committee (PAC) that Mr Callely had yet to send in the bill for his costs, but it was expected to be as much as half a million euro.
Mr Coughlan said the case touched on serious constitutional issues like the separation of powers between the Oireachtas and the judiciary.
And costs in a separate case involving former judge Brian Curtin could be as much as €4m.
Mr Curtin's lawyers have rejected a 'take-it-or-leave-it' costs offer of about €970,000 from the Oireachtas -- around half the amount defence solicitors were claiming.
Mr Curtin faced impeachment proceedings after charges over alleged child pornography possession were dropped.
The former circuit court judge retired on grounds of ill health in November 2006 before he could be called as a witness at an Oireachtas inquiry.
A Dail probe into his fitness to be a judge never held public hearings or quizzed Mr Curtin personally, and was bogged down in legal challenges for the best part of two years. But the Supreme Court awarded the judge his costs, giving the Oireachtas no choice but to pay up.
The committee was also told that abolishing the Seanad would save direct savings of €9.2m.
Mr Coughlan also told the PAC that former education minister Gemma Hussey was paid €1,085 by the Oireachtas to compensate for damage caused to her car in Leinster House.
He also said that every extra day the Dail sat -- such as the new Friday sittings -- €90,000 in costs were incurred and overtime from late-night sittings cost €3m a year.
This led Fine Gael Limerick TD Kieran O'Donnell to suggest the Dail and Seanad should move to sitting hours in line with a normal nine-to-five working day.