The Minister for Communications said a retired High Court judge's review into the GSOC bugging claims goes further than he expected.
Under the inquiry announced last night, John Cooke will be able to call new witnesses and hear oral evidence from whoever he sees fit.
Minister Pat Rabbitte said the review will be fully comprehensive and independent.
He also said he felt John Cooke would ask for narrower terms of reference than he was given.
"When I saw [the terms of reference] first, my immediate instinct was that the retired High Court judge might himself seek to narrow them - but he hasn't."
"Therefore, it is a totally comprehensive, independent inquiry."
In the Dáíl today, Joan Burton also defended the review from vigorous criticism of the opposition, forcing the Ceann Comhairle to threaten suspension of the sitting .