The state forked out 11 million euro on consultants who gave outdated advice to chase a no-win 10 million euro VAT lawsuit through the courts.
Even though the law had been changed reversing a tax break, Campus Stadium Ireland Development (CSID) spent another one million euro trying to recoup construction levies from building the National Aquatics Centre.
A public spending watchdog revealed the extent of the losses run up as public servants went against what it called the correct and common sense advice of both the Attorney General and the Comptroller and Auditor General.
John McGuinness, chairman of the Public Accounts Committee, said the case should never have been taken. "What I find most disheartening is that there appears to be no acknowledgement that mistakes were made right through the handling of this case," he said.
CSID took Dublin WaterWorld all the way to the Supreme Court in a complex tax case chasing 10.25 million euro. It lost in 2010.
Under laws enacted in 2002 the company, which had a 30-year lease on the 74 million euro aquatics centre, was not liable to pay a VAT bill which would only have covered the VAT costs incurred by CSID during construction.
A breakdown of the consultants' costs showed 7.84 million euro spent on professional services and 3.04 million euro spent on executive services from 2000-2010.
Further information supplied to the committee by the Department of Transport, Tourism and Sport in March this year showed six million euro of the total was regarded as professional and legal fees, and more than one million euro for consultants. Legal bills for the CSID lawsuit have run to 240,000 euro and could top one million euro when Dublin WaterWorld's fees are added.
Mr McGuinness said he questioned whether the highly-paid tax advisers gave value for money. "It would seem that the best advice they got was free. Use common sense, stop. And they went along," he said. "It smacks of following on with this just because they could and they had the taxpayers' money."
John Moriarty, chief executive of Dublin WaterWorld, said the CSID board and highly-paid advisers must be called to account for a wanton waste of taxpayers' money and pointless exercise. "CSID and the Department of Sport went all the way to the Supreme Court with unchecked access to taxpayers' money but, regrettably, with no case," he said.